Detailed programme with abstracts
Transcript of Detailed programme with abstracts
4th
ACTRIS General Meeting
June 10-13, 2014, Clermont-Ferrand, France
Meeting Program
Program Overview
Detailed Program with abstracts
Opening
Tuesday, 10 June, 14:00 – 14:30
14:00 – 14:15 Welcome addresses
Patrick Bachelery (OPGC) Joel van Baelen (CNRS - LaMP)
14:15 – 14:30 Introduction
Paolo Laj (CNRS-LGGE/UJF) / Gelsomina Pappalardo (CNR-IMAA)
Oral session S1a: Scientific achievements at ACTRIS stations
Tuesday, 10 June, 14:30 – 17:00
Chairs: Herman Russchenberg, Alfred Wiedensohler
S1.O1 (14:30 – 14:45) Using Cloudnet data to evaluate the representation of clouds in NWP models
A. J. Illingworth and E. J. O'Connor
Cloud data from the recently extended ACTRIS advanced atmospheric observatories
have been compared with the representation of clouds in various nwp models. Skill
scores have been derived which quantify the ability of the weather forecast models
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to predict the right clouds in the right place at the right time; this is a necessary first
step if the models are to predict heavy rainfall events. Both climate and weather
forecasting models use essentially the same cloud parameterisation schemes so the
performance of various schemes in forecast models is a useful guide of their
suitability for use in climate models.
S1.O2 (14:45 – 15:00) Analysis of microphysical properties at EARLINET stations: spatial and temporal evolution during summer 2012 operational exercise M. J. Granados-Muñoz, F. Navas-Guzmán, J. L. Guerrero-Rascado, J.A. Bravo-
Aranda, S. N. Pereira, M. Sicard, L. Belegante, D. Nicolae, A. Papayannis, G.
D’Amico, K. Schepanski, J.M. Baldasano, U. Wandinger, A. Chaikovsky, G.
Pappalardo, C. Muñoz, A. Rodríguez, A. Comerón and L. Alados-Arboledas
In the framework of an exercise to test the operational capabilities of
ACTRIS/EARLINET during Summer 2012, intensive measurements were performed in
July 2012 during a period of 72-hour simultaneously at several ACTRIS/EARLINET
ground-based lidar stations. One of the aims of this exercise regarding lidar
measurements was to obtain an experimental database with vertical resolution for
investigating the aerosol radiative impact over the Mediterranean basin using 3-D
model simulations of African dust. The exercise was held from 9th July at 06:00 UTC
to 12th July at 06:00 UTC, when a mineral dust event was affecting the European
region. Besides the lidar measurements, five of the stations performed coincident
sun photometers measurements following AERONET protocols, i.e. Granada,
Athens, Évora, Barcelona and Bucharest. The combined AERONET/EARLINET
measurements allow here for analysing vertical profiles of microphysical properties
by means of LIRIC (Lidar Radiometer Inversion Code) algorithm. By combining lidar
measurements and AERONET inversion retrievals at the five experimental sites,
volume concentration profiles of fine and coarse particles (spherical and spheroid
when available) are retrieved. The obtained results allow us to analyze both
temporal and spatial evolution of the vertically resolved microphysical properties of
mineral dust during the 3-day intensive measurement period, improving our
knowledge about the different processes affecting mineral dust during its transport.
Data from models such as BSC-DREAM8b, SKIRON, NAAPS and COSMO-MUSCAT
will also be validated by means of these retrievals.
S1.O3 (15:00-15:15) Aerosol Mass Spectrometric Measurements at CESAR-Tower in Cabauw, NL,
P. Schlag, A. Kiendler-Scharr, A. Vermeulen, M. J. Blom, R. Holzinger
Intensive measurements of aerosol chemical composition were performed with an
Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS)
at the Cabauw Experimental Site for Atmospheric Research (CESAR) in Cabauw, NL,
in November 2011 and from May to July 2012. Additionally, an Aerosol Chemical
Speciation Monitor (ACSM) was measuring from July 2012 to June 2013. The CESAR
site is a rural station representative for North-West Europe. Depending on
prevailing wind direction, the condition can be either of maritime or continental
character.
As observed in previous campaigns at the site, nitrate and organics are major
contributors to aerosol mass with their relative importance showing a seasonal
dependence. Inorganic and organic aerosol composition data from the AMS are
compared with Monitor for AeRosol and GAses (MARGA) and a Thermo-Desorption-
Proton-Transfer-Mass-Spectrometer (TD-PTR-ToF-MS), respectively. Evaluating the
inorganic ion balance, we observe periods in which observed NH4+ exceeds the
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NH4+ needed for inorganic anion neutralization. This is taken as indication for the
presence of organic acids in the aerosol. For the first time, Positive Matrix
Factorization (PMF) was used for analysing the aerosol organic fraction derived
from the TD-PTR-MS. These and the PMF results from the HR-ToF-AMS show
similarities in time trends of AMS and PTR-MS factors. That creates new possibilities
to analyse PMF factors with mass spectra from two different ionization techniques.
Main organic aerosol sources and the possibility to quantify organic acids based on
AMS data in environments with high NH3 are discussed.
S1.O4 (15:15 – 15:30) Typifying Air Masses and Sources at Birkenes in Southern Norway by Combining
ACTRIS Observables and Model Tools
M. Fiebig, W. Aaa, S. Solberg, N. Schmidbauer, A.M. Fjæraa, K.E. Yttri, T.
Hamburger, C.R. Lunder, C. Lund Myhre, K. Tørseth, G. Hansen
We propose that a cluster analysis on data from ACTRIS stations can serve as basis
for a pan-European parameterization of aerosol properties as new integrated
ACTRIS product for use in climate modelling. The method is exemplified using
Birkenes atmospheric observatory in Southern Norway, which is uniquely located to
study biogenic boreal forest emissions, long-range transported pollution from
industrialised regions, Arctic in- and outflow, as well as regional emissions in a
sparsely populated Northern landscape, all at the same location. Over the past
years, the Birkenes observation programme, contributing to ACTRIS WP3 and 4, has
been upgraded to now include almost the full list of aerosol parameters
recommended by GAW for long-term observation (particle size distribution,
scattering / absorption coefficient, concentrations of particle mass, major chemical
constituents, and cloud condensation nuclei, columnar optical depth), as well as
gas-phase components such as offline VOCs, CO_2 , CH_4 , O_3 , PCBs, also
precipitation chemical composition. Recently, the programme has been augmented
further to include online aerosol chemical
speciation by ACSM (continuous), and online VOCs by PTR-MS (campaign-based).
Based on the observations of aerosol properties with high (hourly) time resolution,
a cluster analysis is presented that classifies the aerosol types
encountered at Birkenes into 4 classes, while the Lagrangian transport model
FLEXPART locates the footprint, i.e. source regions, of the 4 clusters. The analysis is
augmented by correlation with levoglucosan samples as tracer of
emissions from biomass burning. A further analysis uses 2 intensive campaigns of
PTR-MS VOC observations and the EMEP-WRF modelling system to investigate the
fate of biogenic VOC emissions.
15:30 – 16:00 Coffee break
S1.O5 (16:00 – 16:15) Diurnal and seasonal variability of the atmospheric boundary layer depths over
the suburban SIRTA observatory near Paris: Dynamics and forcing mechanisms
M. Haeffelin and S. Pal
The development and maintenance of the atmospheric boundary layer (ABL) plays a
key role in governing the distribution of atmospheric constituents like aerosols,
greenhouse gases, water vapor, ozone, etc. For instance, the ABL features (e.g.,
depth, turbulent flux, entrainment processes, and growth rate) are important for
understanding air quality impacts of aerosols, and the dispersion and transport of
aerosols confined within the ABL. A detailed understanding of these features based
on long-term measurements of ABL depths is considered challenging but important
for meteorological process studies involving ABL depths.
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A long-term data set of ABL depth time series has been derived at the SIRTA
observatory near Paris, using measurements obtained from a ground-based
vertically-pointing aerosol lidar system and a robust retrieval method. Five years of
observations (2008-2013), are used to investigate both diurnal and seasonal
variability of ABL depths and their correlation to near-surface meteorological
parameters (e.g. near-surface stability condition, humidity, temperature, sensible
heat flux, etc.). We found that the day-to-day variability in the ABL depths to be
affected not only by site-specific meteorological conditions (e.g. solar radiation,
precipitation, low-level cold-air advection, near-surface meteorological
characteristics), but also by land-surface characteristics, cloud cover, dynamical
features associated with the interplay between residual layer and the nocturnal
boundary layer (NBL), and synoptic conditions. Additionally, the ABL depths show
larger day-to-day variability on fair weather days than on cloudy and synoptically-
disturbed days on which ABL depths are poorly defined. For instance, the process of
destruction of the inversion layer is defined as the breakup of the temperature
inversion which is destroyed predominantly by the upward growth of a convective
boundary layer from the ground. By analyzing diurnal-cycle composites of ABL
depths, we document characteristic features of the driving factors that determine
both diurnal and seasonal variability in the daytime CBL depths over SIRTA.
S1.O6 (16:15 – 16:30) Phenomenology of aerosol absorption at Montseny (regional background) and
Montsec (mountaintop) stations in NE Spain
M. Pandolfi, N. Pérez, A. Ripoll, X. Querol, M. C. Minguillón, and A. Alastuey
(IDAEA-CSIC, Barcelona, Spain)
Aethalometer (AE31 and AE33) and MAAP instruments were deployed to
investigate time trends, seasonal dependence and diurnal cycles of aerosol
absorption at Montseny (MSY; regional background; 720 m a.s.l.) and Montsec
(MSC; remote; 1570 m a.s.l.) stations in NE Spain. The multiwavelenght
Aethalometer data were used to apportion aerosol absorption, black carbon (BC),
elemental carbon (EC) and organic carbon (OC) concentrations to fossil (ff) and
non‐fossil (biomass burning; bb) sources. Results showed that the Aethalometer
source apportionment appeared to be more robust for apportioning the
contributions of each source to BC and EC rather than to OC probably as a
consequence of the high biogenic contribution to OC concentrations at MSY and
MSC stations. Aerosol absorption data from MAAP and EC concentrations from
filters were used for the determination of the mass absorption cross section (MAC)
at both measurement sites. The results show that the MAC was clearly a function of
seasons and air mass origin at both sites indicating changes in the microphysical
properties of absorbing particles depending on aerosol type and aging. In order to
investigate the reasons for the observed variation of the MAC chemical speciated
PM data from filters (24h resolution) and from an ACSM instrument (30 min
resolution) were used. Finally, the data collected at MSC station, frequently in the
free troposphere, were used to investigate the importance of mineral matter
(mainly Iron) absorption on MAAP data.
S1.O7 (16:30 – 16:45)
ACTRIS intercomparison experiment of volatile organic compounds in Europe
C. C. Hoerger, A. Werner, C. Plass-Duelmer, S. Reimann, E. Eckart, R. Steinbrecher,
J. Arduini, N. Bonnaire, J. N. Cape, A. Colomb, R. Connolly, J. Diskova, P. Dumitrean,
C. Ehlers, V. Gros, H. Hakola, M. Hill, J. R. Hopkins, J. Jäger, R. Junek, M. Leuchner,
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A. C. Lewis, M. Maione, D. Martin, K. Michl, E. Nemitz, S. O'Doherty, S. Sauvage, N.
Schmidbauer, T. G. Spain, E. Straube, M. Vana, M. K. Vollmer, R. Wegener, A.
Wenger
During 2012, the performance of 20 European laboratories involved in long-term
VOCs measurements within the framework of GAW and EMEP was assessed with
respect to newly determined ACTRIS data quality objectives (DQOs). Compared to
previous intercomparisons the DQOs of ACTRIS are much more demanding
(deviations of max 5% to a reference value). The participants were asked to
measure a 30 component VOCs mixture (including alkanes, alkenes, alkynes, and
aromatic compounds) in nitrogen at about 1 nmol/mol and whole air following a
standardised operation procedure. For VOCs in nitrogen 61% of the FID- and 51% of
the MS-results were within the ACTRIS DQOs. For whole air slightly more scatter
was observed. The results of the analytical systems are discussed with respect to
calibration issues, FID and MS detection, sample matrices, breakthrough,
adsorptive losses, and chromatographic resolution. The results of monoterpenes
and trimetylbenzenes are shown in an accompanying poster by Werner et al.
S1.O8 (16:45 – 17:00)
ParisFog: a research program to better understand the fog processes combining
in-situ and remote-sensing instrument at SIRTA ACTRIS observatory
J-C. Dupont, M. Haeffelin, T. Elias, J. Delanoe, F. Burnet, J. Sciare, E. Dupont, P.
Goloub, T. Bourcy, F.Zanghi
Fog life cycle is driven by the competing interactions between thermodynamics,
dynamics, microphysics, radiative fluxes and chemistry all of which are difficult to
model. Therefore, the goal of this work is to combine in-situ sensors, active, and
passive remote sensing instruments to better understand dynamical, radiative,
thermal and turbulent processes modulating the different phases of the fog life
cycle.
The understanding of the physical processes needs to have precise retrievals along
the vertical for droplet and aerosol microphysical properties. So, in this presentation
we will focus on lidar and cloud radar algorithms for comparison with in-situ sensor
at the surface and retrieval along the vertical.
In a second part, we will present and quantify the critical values that key variables
must take to lead to fog formation and fog dissipation for all the different Low
Visibility Events (LVE) considered in this study. The statistical analysis used the
unique and coherent dataset derived from the in-situ, passive and active remote
sensing instruments deployed during the ParisFog field experiment since 2006 at
SIRTA observatory [Haeffelin et al., 2005, 2010].
Poster session P1: ACTRIS Integration activities
Tuesday, 10 June, 17:00 – 19:00
P1.1 EARLINET/ACTRIS support to the summer 2013 ADRIMED/ChArMEx campaign
Michaël Sicard, Constantino Muñoz, Adolfo Comerón, Lucas Alados‐Arboledas, Aldo Amodeo, Antonella Boselli, Giuseppe D'amico, María José Granados‐Muñoz, Giuseppe Leto, Juan Luís Guerrero‐Rascado, Fabio Madonna, Lucia Mona, Gelsomina Pappalardo, Maria Rita Perrone, Simona Scollo, Nicola Spinelli, Gloria Titos, Xuan Wang, Ricardo Zanmar Sanchez
In the framework of the ChArMEx (Chemistry‐Aerosol Mediterranean Experiment,
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http://charmex.lsce.ipsl.fr/) initiative, a field campaign took place in the western
Mediterranean Basin between 10 June and 5 July 2013 within the ADRIMED
(Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean
region) project. The scientific objectives of ADRIMED are the characterization of
the typical “Mediterranean aerosol” and its direct radiative forcing (column
closure and regional scale). At three sites, in Ersa (Corsica Island, France),
Granada (Spain) and Lampedusa (Italy), a complete set of instruments were
operated to measure in‐situ aerosol physical, chemical and optical properties.
Aerosol mixing state and vertical distribution, as well as radiative fluxes were also
measured. At a third site, in Menorca (Spain), aerosol optical properties and
vertical distribution were measured. The ground observations were supported by
airborne measurements: the ATR‐42 (10 June – 5 July) and the Falcon‐20 (17 June
– 5 July) equipped with a lidar. In several occasions corresponding to aerosol loads
of different types the aircrafts flew near EARLINET/ACTRIS lidar stations: near
Barcelona and Granada on 16 and 17 June, near Barcelona on 18 and 27 June,
near stations in southern Italy (Potenza, Naples, Lecce, Serra La Nave) on 22, 23,
28 June and 2 July. Whenever it was possible, extra measurements were carried
out by the EARLINET/ACTRIS lidar stations. The presentation will focus on the
situations covered simultaneously by airborne and ground‐based lidar
measurements.
P1.2 On the usefulness of ceilometers for aerosol monitoring
Matthias Wiegner and Alexander Geiß
With the implementation of ceilometer networks by national weather services a
discussion started to which extent these simple backscatter lidars can be used for
aerosol research. Though primarily developed for the detection of clouds several
publications show that at least observations of the vertical structure of the
boundary layer might be possible. Quantitative retrievals of optical properties of
particles are, however, restricted to the backscatter coefficient βp. These
retrievals require the calibration of the ceilometer.
Calibration is possible, if issues as incomplete overlap, sampling properties when
compared to sun photometer measurements, the unknown lidar ratio, and water
vapor absorption are carefully considered. EARLINAT lidars can be of great help
for calibration purposes. For the derivation of βp forward and backward
integration methods are available – with different performance with respect to
accuracy and applicability. An extended discussion of the different options can be
found in Wiegner et al. (2014). Under favorable conditions the uncertainty of βp
will remain below 10%, a high temporal resolution of a few minutes can be
achieved, and near real time applications are possible.
Calibrated signals are also beneficial for basic applications such as the assessment
of the mixing layer height or the detection of elevated aerosol layers. The
combination of methods for edge detection and edge tracking techniques results
in a high reliability. Consequently, and as the maintenance costs of ceilometers
are low and operation is fully automated, long term observations of the
stratification of the tropospheric aerosols are feasible.
P1.3 Major updates and improvements of the EBAS database and web portal
T. Hamburger, M. Fiebig, P. Eckhardt, W. Aas, A.M. Fjæraa, C. Lund Myhre, K.
Tørseth
The EBAS database hosts observational data of atmospheric chemical and
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physical properties. The increase in content and usage by a multiplicity of different
groups led to a growing demand on the database functionality. Several
improvements and changes concerning the database core and user interface were
determined and implemented to support the present and future requirements on
the EBAS database.
Within the new implementation a suite of new tools have been developed to
support the QA/QC process and for extracting statistical information.
The data export format is adapted to user suggestions to improve the
interoperability with further applications. Mass download and scheduled data
transfer is implemented for several projects. Amongst others, a regular data
export for Met.no (aerosol NRT data) and HTAP (quarterly extract) as well as a
daily extract for the ECMWF and MACC project is set up.
New implementations in the EBAS web interface improves the performance and
usability of the web application during start up and data selection. Several bugs
are corrected in the web representation of EBAS and its online visualisation tools.
Within the development of the ACTRIS Data Centre new online visualisation
methods are implement and will be ported to the EBAS web interface in the
future.
One of the main new features is the improved usage of metadata elements.
New metadata elements are added to support the version control of datasets.
This allows for a full history of the database and data sets, to track data updates
and retrieve historic data versions. Metadata elements can be time-dependent
and changes can be tracked. Hence, integration into e.g. INSPIRE and GCOS are
therefore enabled. The new metadata features improve the traceability of the
data processing back to their observations. In addition, new metadata elements
were implemented to support descriptions for advanced aerosol observations as
part of GAW-WDCA.
We will present the features and updates of the new EBAS database and web
application at the ACTRIS GA.
P1.4 Testing for loading effects in filter photometers – how to avoid assumptions
altogether
G. Močnik, L. Drinovec, T. Hansen, S. Segura, V. Estellés, G. Titos, H. Lyamani, M.P.
Utrillas, P. Zotter, A.S.H. Prévôt, L. Alados-Arboledas, J.A. Martínez-Lozano, A.
Polidori, M. Rupakheti, G. Schauer
Filter absorption photometer measurements are affected by loading effects which
need to be compensated. Various compensation methods relied mostly on the
continuity of data (Weingartner et al. 2003; Virkkula et al., 2007; Hyvärinen et al.,
2013) to derive the compensation parameters. Here we propose a more robust
method to determine the quality of the compensation for loading effects: the
slope of the absorption coefficient vs. the loading of the spot. This method was
used to compensate the BC measurements (Park et al., 2010), but here we use it
as an independent criterion to evaluate the compensation. This criterion does not
use any assumptions or external data, only the measurements from a single
instrument by checking the measured parameters for internal consistency. For a
long period of homogeneous measurements in terms of the sources and
meteorology, the absorption coefficient should not depend on the loading of the
spot. The uncompensated measurements of mass equivalent Black Carbon in filter
photometers are proportional to the time derivative of the attenuation of
detected light intensity (MAAP: in reflection; Aethalometer: in transmission), not
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on the absolute attenuation values. Any dependence of the measured absorption
on the loading (attenuation) is evidence of a bias due to the loading of the spot.
The parameter, which was shown to be most representative of these effects, is the
slope of the attenuation or absorption coefficient or attenuation coefficient as a
function of the loading. We will demonstrate the usefulness of this method as an
independent criterion of the compensation for several absorption photometers
from different campaigns: the MAAP, Aethalometer AE31, AE33.
P1.5 ACTRIS mass closure experiments for gaseous and particulate carbons at
different stations in Europe
C. C. Hoerger, S. Reimann, M. Hill, A. Werner, C. Plass-Duelmer, J. K. Gietl, K.
Michl, M. Crippa, A. Prévôt, N. Bonnaire, A. Borbon, V. Gros, N. Marchand, V.
Riffault, S. Sauvage, J. Sciare, A. Setyan, B. Bandy, J. R. Hopkins, D. C. Green, D.
Young
A new approach for holistic consideration of the total observed organic carbon
(TOOC) budget will be shown at different sites in Europe. Similar budget
approaches are routinely used for nitrogen oxides and sulfur in the atmosphere,
and rapidly improving measurement techniques (such as ACSM or PTR-MS) are
beginning to make this possible for organic carbon. The organic carbon budget
includes a large group of compounds, with many that are likely to contribute have
hardly been observed under ambient conditions. Therefore, the combined analysis
of gaseous compounds, which play an important role in the chemistry of the
troposphere, and particles, which are a climate forcing agent, is an important
issue. This mass closure of atmospheric organic carbon will be achieved by
bringing together state-of-the-art equipment for both gaseous and particulate
organic substances (GC-FID/GC-MS/PTR-MS/ACSM). Preliminary TOOC-results of
some sites, which were involved in EMEP intensive campaigns, MEGAPOLI, or
ClerFlo, will be presented.
P1.6 Intercomparison of ME-2 source apportionment results from 15 co-located
aerosol mass spectrometers from the ACTRIS-ACSM network
Roman Fröhlich, Vincent Crenn, Francesco Canonaco, Jay G. Slowik, Olivier Favez,
Wenche Aas, Mikko Äijälä, Begoña Artiñano, Claudio A. Belis, Michael Bressi,
Claudio Carbone, Esther Coz, Philip L. Croteau, Michael J. Cubison, Johanna K.
Gietl, David C. Green, Liine Heikkinen, John T. Jayne, María C. Minguillón, Colin D.
O’Dowd, Jurgita Ovadnevaite, Ettore Petralia, Laurent Poulain, Max Priestman,
Véronique Riffault, Anna Ripoll, Roland Sarda-Estève, Ari Setyan, Urs
Baltensperger, Jean Sciare and André S. H. Prévôt
14 mass spectrometers for on-line aerosol particle chemical composition
measurements (13 Quadrupole ACSM, 1 ToF-ACSM) from the ACTRIS-ACSM
network (http://www.psi.ch/acsm-stations) and one HR-ToF-AMS were gathered
at the SIRTA site in Gif-sur-Yvette, approximately 20km southwest of Paris. From
15.11.2013 to 02.12.2013 all 15 instruments measured ambient aerosol in parallel
and with the same settings with the aim to improve the understanding of the
measurement technique and its related uncertainties
This presentation focuses on the intercomparison of widely and successfully used
positive matrix factorization (PMF) source apportionment strategies for aerosol
mass spectrometer data (Paatero & Tapper, 1994; Lanz et al., 2007) using the
new source finder (SoFi, Canonaco et al., 2013) toolkit based on the Multi-linear
Engine 2 (ME2) solver.
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Fig. 1 summarizes the 4-factor source apportion-ment results, generated
individually for each dataset of the 15 instruments using optimized a-values for
HOA and COA, with anchor mass spectra taken from a previous campaign at the
same site (Crippa et al. 2013). The average contributions of the factors to the total
organics are: HOA: 14.8±2.3%; COA: 16.0±2.6%; OOA: 39.4±4.9%; BBOA:
31.0±3.5%. These results present an accuracy of the source apportionment factors
across the 15 different instruments of about ±20%.
Several other parameters like the variability of the individual factor mass spectra
or the influence of the employed reference spectra were explored as well.
P1.7 Atmospheric Observatory Eastern Mediterranean
L. Barrie, Nikos Mihalopoulos, H.C. Hansson, Vangelis Gerasopoulos, Jean Sciare,
M. Vrekoussis, S. Kleanthous, Zev Levin
The Eastern Mediterranean is a unique yet poorly observed region for atmospheric
chemistry. Surrounded by the diverse ecosystems and populations of southern
and Eastern Europe, the Middle East and North Africa, it experiences a diverse
mix of anthropogenic, biogenic and natural aerosols. Sand and dust storms from
northern Africa, the Gulf region and Middle East are frequent and severe. Aerosols
from biomass burning fires in the arid summer half of the year is common.
Anthropogenic sulphates, nitrates and organics are produced from gas to particle
conversion and advected into the region from many sources. These aerosol types
often mix with sea salt aerosols in the moist planetary boundary layer of the
Mediterranean.
Although there are comprehensive air chemistry observations at individual
stations over the region that are registered with ACTRIS, they are largely
uncoordinated. In Crete, the Finokalia station has been operating for twenty
years. In Cyprus, the Agia Marina station has been operating as a regional station
in the Cooperative Programme for Monitoring and Evaluation of the Long-range
Transmission of Air Pollutants in Europe (EMEP) for over 15 years and is imbedded
in a 9 station environmental network. In addition in Cyprus, there is an aerosol
remote sensing LIDAR and AERONET photometer operated under ACTRIS as well
as Unmanned Aircraft operated under the European project BACCHUS.
In the Peloponnese region of western Greece, the Navarino Environmental
Observatory has been measuring aerosols for several years. It is proposed that a
consortium focusing on the Atmospheric Observatory Eastern Mediterranean is
developed as part of the future European aerosol and atmospheric chemistry
observing infrastructure. One key goal is to utilize existing expertise in the
consortium to build capacity for atmospheric observations and research in the
region.
P1.8 Atmospheric Station and UAV Facilities in Cyprus: A New Tool for Coupling In-
Situ, Remote Sensing And Vertical Atmospheric Observations
L. Barrie, M. Vrekoussis, S. Kleanthous, J. Sciare, N. Mihalopoulos, Z. Levin, M.
Lange, M. Argyrides, S. Ioannou, C. Keleshis, R. Sarda-Estève, F. Dulac, G. Roberts,
M. Mallet, G. Mocnik
The island of Cyprus is strategically located at a crossroads of air streams from
Europe, Africa and the Middle East that have contrasting aerosol-related
emissions from natural and anthropogenic sources. It is in a Mediterranean region
where climate changes (e.g. heat waves and droughts) are expected to be among
the highest globally (IPCC, 2011). Also, Cyprus experiences a large number of dust
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storms originating from Africa, the Gulf region and the Middle East which
exhibiting different and poorly characterized aerosol optical properties (Mamouri
et al., 2013).
Since the late nineties, long term observations of key atmospheric chemistry
variables (O3, NOx, PM) have been initiated in Cyprus, at the “Agia Marina
Xyliatou” station (Figure 1) operated by the Department of Labor Inspection as a
European Monitoring and Evaluation Programme (EMEP) station focusing on
long-range transboundary air pollution (Kleanthous et al., 2014). As part of the
ENVIMED “CyAr” project (component of the French ChArMEx program;
http://charmex.lsce.ipsl.fr/), this station will be equipped by mid 2014 with a new
set of real-time in-situ aerosol instruments (Q-ACSM, 7-l aethalometer, 3-l
nephelometer, OPC, SMPS, CCN counter) offering new perspectives on aerosol
(PM) sources and their geographical origin downwind of major non–EU countries
surrounding the Mediterranean (Turkey, Lebanon, Israel, Egypt) as well as on
properties of sand and dust storms.
In parallel, the Cyprus Institute (CyI) has developed a fleet of Autonomous
Unmanned Aerial Vehicles (UAV, Figure 2) equipped with ultra-light aerosol
sensors (absorption, number size distribution electrostatic precipitator for ice
nuclei) to measure vertical profiles. As part of the EU-FP7 BACCHUS project
(http://www.bacchus.ethz.ch/) and in conjunction with LIDAR observations
performed by the Cyprus University of Technology, the UAVs will be deployed from
spring 2015 to investigate ice nuclei (IN) and cloud condensation nuclei (CCN) and
other aerosol properties.
The coupling between the ground based measurements at Agia Marina Xyliatou
Station and UAV vertical profiles will constitute a unique new data sets to
characterize the respresentativeness of the surface in situ measurements.
As a proof of concept, new light multi-wavelength absorption sensors are being
tested on the CyI UAVs in 2015 and compared with similar sensors at ground level
to explore the spectral absorption dependence of African and Middle Eastern dust
particles. These vertical absorption measurements will help to constrain and
calibrate aerosol remote sensing instrumentation operated by the ACTRIS
community.
P1.9 Preliminary results of testing of regularization algorithm for data processing of
Raman and polarization lidar measurements
Anatoli Chaikovsky, Oleg Dubovik, Sergei Denisov, Yan Grudo, Anton Lopatin,
Yana Karol
Recent talk presents preliminary results of testing of new version of LIRIC (Lidar
and Radiometer Inversion Code) software package. Retrieving of aerosol
parameters from lidar data has properties of ill-posed inverse problems, as soon
as we turn from single-wavelength solutions of the lidar equation to processing
data of complex measurements. LIRIC inversion algorithm and program package
for retrieving concentration of aerosol modes from combined lidar and radiometer
data has been improved to process data of Raman and polarization lidar
measurements using common statistical regularization technique. Specific
program module for estimation of the uncertainty of the solutions has been
developed and included into the LIRIC package. Output database was modified to
include additional retrieved parameters.
P1.10 Canister experiment during the ACTRIS NA 4 VOC Round Robin intercomparison
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S. Sauvage, N. Locoge, S. Dusanter, C. C. Hoerger, A. Werner, C. Plass-Duelmer, S.
Reimann, E. Eckart, R. Steinbrecher
Non-Methane Hydrocarbon compounds (NMHCs) are tracers of both biogenic and
anthropogenic emission sources and play a key role in the atmosphere as
precursors of ozone or secondary organic aerosols. The importance of these
species for understanding atmospheric chemistry is recognized by the research
community and high-quality and long-term observations are needed to tackle
issues of air quality and climate change. Among methods to measure NMHCs,
whole air sampling in stainless steel canisters remains widely used within the
EMEP and GAW networks.
We included this method in the ACTRIS VOC Round Robin intercomparison
organized in 2012 to assess the reliability of this off-line method together with on-
line instrument testing at concentration levels of NMHCs around 1ppb. Samples in
canisters were analyzed by GC/FID to quantify 30 compounds from C2 to C9. The
results show a good agreement with online measurements for most compounds,
confirming the reliability of this method for monitoring volatile organic
compounds at low levels. It was also the opportunity to test the effect of several
parameters, namely the humidity of the sample, the canister pressure, and the
stability of the sample over time. These results are useful to better estimate the
measurement uncertainty.
P1.11 Intercomparison of ambient BVOC measurements: What useful information can
we infer for the ACTRIS program?
V. Michoud, S. Dusanter, S. Sauvage, N. Locoge, V. Gros, T. Léonardis, B. Bonsang,
C. Kalogridis
Biogenic Volatile Organic Compound (BVOCs) are of prime interest for long term
monitoring since these species contribute to the loading of organic carbon at
remote sites and are useful to evaluate models of atmospheric emissions. It is
therefore important to assess whether reliable measurements of BVOCs can be
performed using current techniques, which in turn will help assessing data quality
in measurement networks such as ACTRIS.
An intercomparison involving three online gas chromatographs, an automatic
cartridge sampler, and a Proton Transfer Reaction-Time of Flight Mass
Spectrometer from Mines Douai and the Laboratoire des Sciences du Climat et de
l’Environnement took place during Summer 2013 at Cap Corsica (France) as part
of the ChArMeX field campaign. These instruments measured continuously
ambient concentrations of isoprene and several monoterpenes (α- and β-pinene,
limonene, α- and γ-terpinene, camphene) for a duration of three weeks.
Collocated measurements have been compared to assess the reliability of BVOC
monitoring and to identify potential measurement artifacts. These results suggest
a good agreement between several techniques for isoprene but some differences
are observed for α- and β-pinene, as well as limonene. Some recommendations
will be provided for monitoring these species.
P1.12 ACTRIS carbonaceous data quality assessed over the years 2007-2013.
Fabrizia Cavalli and Jean-Philippe Putaud
Inter-laboratory comparison exercises for total and elemental carbon
measurement have been regularly organised in the framework of the EU-projects
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EUSAAR and ACTRIS over the period 2007-2013. The main objective has been to
assess the quality of data produced by individual site and in particular, to identify
and correct possible procedural and instrumental biases, derive site-specific
harmonisation factors and produce a highly comparable dataset at all sites.
Initially, the overall data comparability has substantially increased because of the
adoption of the common thermal-optical protocol EUSAAR_2 and the
implementation procedural recommendations.
Most recent exercises have revealed only slightly, if at all, improvements. The non-
negligible variability still existing in total carbon determination appears to be
user-dependent, whereas that one, even more pronounced, in the elemental
carbon determination is mainly due to an inter-instrument variability.
P1.13 Pathfinder: MLH temporal development tracking applying Dijkstra’s graph
search algorithm
Marco de Bruine , Arnoud Apituley, Fred Bosveld, Henk Klein Baltink
The height of the atmospheric boundary layer, or mixing layer (MLH) is an
important parameter for understanding the dynamics of the atmosphere and
dispersion of air pollution. Mixing layer heights can be retrieved from backscatter
lidar or ceilometer data. Various algorithms have been proposed, that all have in
common that the atmospheres aerosol content is used as a tracer for the layering
structure in the atmosphere. Although it is possible to detect gradients in the
vertical backscatter profile under most circumstances, the challenge lies in the
correct attribution of the detected gradients to the actual MLH. Tracking the MLH
can be challenging in complex cases, such as under the presence of residual layers
of air pollution above the MLH or during and after periods of rain. We pre--‐ sent a
new approach using Dijkstra’s graph search algorithm [Dijkstra, 1959] to be able
to find the optimal temporal development of the MLH. We show results from our
new ‘Pathfinder’ algorithm applied to Leosphere ALS450 data and veri--‐ fy the
results using wind profiler turbulence data and sounding profile retrievals
(Richardson bulk). Furthermore, we compare against MLH results from STRAT2D
[Morille, 2007] applied to the same data. We find that the Pathfinder approach
outperforms STRAT2D in particular during the periods of the development of the
MLH in the morning and in the evening. Also, during periods of broken clouds, we
find Pathfinder is able to better follow the development of the MLH. We hope to
be able to show some cases comparing to MLH retrievals from Doppler lidar data
[Harvey, 2013] as this will provide a better independent verification of turbulent
atmospheric structures. References E. W. Dijkstra, A note on two problems in
connexion with graphs, Numerische Mathematik, Vol. 1:1, pp 269--‐271, 1959
Morille, Y., M. Haeffelin, P. Drobinski, J. Pelon, 2007: STRAT: An automated algo--‐
rithm to retrieve the vertical structure of the atmosphere from single--‐channel
lidar data. Journal of Atmospheric and Oceanic Technology, 24, 761--‐775. Harvey,
N.J., Hogan, R.J., Dacre, H.F., A method to diagnose boundary--‐layer type using
Doppler lidar, Q. J. R. Meteorol. Soc. 139: 1681 – 1693, 2013.
P1.14 Earlinet intensive observation period during summer 2012
N. Papagiannopoulos, G. D’amico, A. Giunta, G. Pappalardo, L. Alados Arboledas,
A. Amodeo, L. Belegante, M. Iarlori, D. Lange, R.E Mamouri, M.A.P. Mcauliffe, D.
Nicolae, P. Kokkalis, J. Preissler, J. Putaud, J.L. Guerrero Rascado, V. Rizi, A.A Ruth,
M. Sicard, F. Wagner, L. Mona
13
An ACTRIS measurement campaign was organized during summer 2012, 8 June –
17 July. ACTRIS and EMEP closely worked together to coordinate this field
campaign which was mainly aimed at the study of Saharan dust particles. Besides,
this intensive observation period (IOP) featured two international field campaigns
during summer 2012 to optimize any possible cooperation. The ChArMEx (The
Chemistry-Aerosol Mediterranean Experiment, https://charmex.lsce.ipsl.fr/)
campaign was held in the period of from 8 June – 12 July and the PEGASOS (Pan-
European Gas-AeroSOLs-climate interaction Study, http://pegasos.iceht.forth.gr/)
campaign provided detailed measurements for the period from 8 June - 9 July.
The main objective of the EARLINET/ACTRIS campaign during summer 2012 was
to investigate the 3-D distribution of European atmospheric aerosols in the
context of Saharan dust intrusion events. The whole network participated in the
campaign performing EARLINET regular measurements. Additional measurements
were performed after alerts concerning the occurrence of special events over
Europe. 10 selected ACTRIS lidar stations performed daily lidar-profiling
measurements around sunset for the whole 8 June – 17 July 2012 period. The
availability of EARLINET vertical profiles of the aerosol optical properties during
the selected period strongly enhanced the collection of a unique, high quality data
set on aerosol, as gathered by a set of sophisticated instruments across Europe.
The description of aerosol type distribution over Europe during the campaign was
obtained through a combined use of advanced lidar measurements, backward
trajectory analyses and model outputs. In particular, two intense African dust
outbreaks were noted and studied into details.
P1.15 In-situ sampling and column remote sensing
Stefan Kinne
Many ACTRIS efforts monitor (sparsely distributed) atmospheric detail near the
surface. This has a lot of relevance to pollution and air-quality. But in order to
extend the value of these samples in space and time, ties to satellite data (with
quasi global coverage) are sought. This was also the reason of in-situ data to
characterize aerosol via optical (and microphysical) properties as those properties
are also derived from column remote sensing. Unfortunately, in-situ samples have
an upper size cut-off, the investigated aerosol is dried (water loss) and aerosol
properties at the ground often divert from aerosol for the entire column,
especially in cases of (advected) aerosol layers at higher altitudes. Thus even at
locations, where in-situ and ground remote sensing (usually the reference to
satellite remote sensing due to high accuracy) are co-located, matches for aerosol
composition (via co-single scattering albedo for absorption or asymmetry-factor
for size) are unlikely to match.
Aerosol compositions by in-situ optical sampling are statistically compared at
several ground sites to corresponding properties from remote sensing. The offsets
between both methods are at best qualitative similar. Quantitatively, statistical
offsets vary almost randomly by month and site. Unable to establish simple links
to aerosol optical properties from satellite data, the impact by in-situ aerosol
optical sampling to climate is at best limited. On the other hand regional air-
quality and health issues are nowdays of high(er) interest. And here in-situ data
can play an important role, especially when successfully tied to satellite remote
sensing that is sensitive to aerosol near surface properties.
P1.16 Pan-Eurasian experiment (PEEX) establishing a process towards high level pan-
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Eurasian atmosphere-ecosystem observation networks
H.K. Lappalainen, T. Petäjä ,N. Zaytseva, T.Laurila, G. De Leeuw, Y. Viisanen, V.
Kotlyakov, N. Kasimov, V. Bondur, G. Matvienko, Alexander Baklanov, Guo
Huadong, P. Hari, S. Zilitinkevich And M. Kulmala
Pan-Eurasian Experiment (PEEX) is a new multidisciplinary research approach
aiming at resolving the major uncertainties in the Earth system science and global
sustainability questions in the Arctic and boreal Pan-Eurasian regions and in China
(http://www.atm.helsinki.fi/peex/, Kulmala et al. 2011). PEEX initiative is built on
a bottom-up initiative by several European, Russian and Chinese research
organizations and institutes. The research program is aimed to solve the scientific
questions that are specifically important for the Northern Pan-Eurasian region in
particular the global climate change, its consequences to nature and Northern
societies. Pan-Eurasian region represents one the Earth most extensive areas of
boreal forest and the largest natural wetlands, thus being a significant source
area of trace gas emissions, biogenic aerosol particles, and source and sink area
for the greenhouse gas (GHG) exchange in a global scale (Guenther et al. 1995,
Timkovsky et al. 2010, Tunved et al. 2006, Glagolev et al. 2010). Furthermore,
PEEX is focused and the strategic and practical solutions for the improved air
quality in China megacities, the important sources of anthropogenic emissions in a
global scale.
The first implementation activities of the PEEX RI initiative is to establish a
process towards high level Pan-Eurasian Observation Networks. Siberian region is
currently lacking a coordinated, coherent ground based atmosphere-ecosystem
measurement network, which would be crucial component for observing and
predicting the effects of climate change in the Northern Pan-Eurasian region. The
first set of stations have been selected for the PEEX Observation network: the
SMEAR-type stations in Finland (SMEAR-I-II-II-IV stations), Estonia (SMEAR-
Järviselja) and China (SMEAR-Nanjing), 6-10 stations in Russia and four ecosystem
stations in China. The concept of the Pan-Eurasian network is based on a
hierarchical SMEAR-type (Stations Measuring Atmosphere-Ecosystem
Interactions) integrated land-atmosphere observation system (Hari et al. 2009).
The ground stations will have a minimum instrument setup and data processing
for atmospheric /forest / peat land/ aquatic / urban monitoring while the flag
ship stations will cover the full setup of instruments and data systems for
monitoring the energy flows in the land –atmosphere continuum. The ground
based observation setup would be completed by the remote sensing observations.
PEEX will bring the observation setup into international context with the
standardized or comparable procedures. Procedures for improved data quality
will be developed in coherence to “The European Strategy Forum on Research
Infrastructures” (ESFRI) process and in collaboration with the “Integrated Carbon
Observation System” research infrastructure (ICOS-RI), “Aerosols, Clouds, and
Trace gases Research InfraStructure Network” (EU-FP7-ACTRIS-I3 project),
“Analysis and Experimentation on Ecosystems” (EU-FP7- Preparatory Phase of
AnaEE), Life Watch (European research infrastructure on biodiversity) and
Svalbard Integrated Earth Observing System (SIOS).
REFERENCES
Glagolev M.V., Kleptsova I.E., Filippov I.V., Kazantsev V.S., Machida T. & Maksutov
Sh.Sh. 2010b. Methane Emissions from Subtaiga Mires of Western Siberia: The
“Standard Model” Bc5. Moscow University Soil Science Bulletin 65: 86--93.
15
Guenther A., Hewitt C.N. Erickson D., Fall R., Geron C., Graedel T., Harley P.,
Klinger L., Lerdau M., Mckay W.A., Pierce T., Scholes B., Steinbrecher R. Tallamraju
R., Taylor J. & Zimmerman P. 1995. A global model of natural volatile organic
compound emissions. J. Geophys. Res. 100: 8873--8892.
Hari, P., Andreae, M. O., Kabat, P. & Kulmala, M. 2009: A comprehensive network
of measuring stations to monitor climate change. Boreal Env. Res. 14: 442–446.
Kulmala M., Alekseychik P., Paramonov M., Laurila T., Asmi E., Arneth A.,
Zilitinkevich S. & Kerminen V.-M. (2011). On measurements of aerosol particles
and greenhouse gases in Siberia and future research needs. Boreal Env. Res. 16:
337-362.
Timkovsky I.I., Elanskii N.F., Skorkhod A.I. and Shumskii R.A. 2010. Studying of
biogenic volatile organic compounds in the atmosphere over Russia. Izvestiya
Atmospheric and Oceanic Physics 46: 319--327.
Tunved P., Hansson H.-C., Kerminen V.-M., Ström J., Dal Maso M., Lihavainen H.,
Viisanen Y., Aalto P.P., Komppula M. & Kulmala M. 2006. High natural aerosol
loading over boreal forests. Science 312: 261--263.
P1.17 Measurements at the Radiative Transfer Laboratory at the University of
Warsaw.
Krzysztof Markowicz, Iwona Stachlewska, Hanna Pawlowska
We present the Radiative Transfer Laboratory of the University of Warsaw - a
research infrastructure dedicated to measure aerosol optical properties their
impact on radiative equilibrium.
The main motivation for this study is a low degree of understanding of the
absorbing aerosol vertical distribution, as well as the climatology and the air mass
modification over Central-Eastern part of Europe. In this part of Europe the high
level of pollution due to a significant anthropogenic emission is accompanied by
large biomass burning activity in the Eastern Europe.
Our Radiative Transfer Laboratory includes two sites which are equipped with in-
situ and remote sensing instruments. The Research Station in Warsaw (52.212 N,
20.983 E, 110 m a.s.l. ) is localized in the city at the University’s campus. In-situ
observations of aerosol optical properties are affected by local emission from
traffic, and surrounding buildings. This site provides an opportunity to study the
impact of mega-city emissions on the columnar and surface optical properties.
The mean impact of the Warsaw's emission on the total AOD at 500 nm is about
0.02 (10-15%). The Research Site in Strzyzow (49.8786oN, 21.8613oE, 443 m
a.s.l.) is localized in South-Eastern part of Poland at the top one of the Carpathian
Mountains peaks and thus represents rural atmospheric conditions. Significant
distance from pollution sources (25 km from the largest city - Rzeszow) facilitates
representative studies for a wide geographic area. The station in Strzyzow is used
as a reference site for remote sensing and in-situ observations of the aerosol
interaction with its impact on the radiation budget. Strzyzow is located in the area
where there is a lack of experimental facilities dedicated to atmospheric research
in this part of Europe. Since Aug 2013 this site is also in the AERONET network.
Infrastructure of the University of Warsaw includes active remote sensing
16
instruments (eight channels PollyXT lidar, CHM15K Ceilometer), passive devices
(CIMEL, Microtops, MFR-7 sun photometers), solar and infrared radiometers,
aerosol in-situ optical instruments (micro-AE51 and AE31 aethalometer, Aurora
polar nephelometer, Photoacoustic Extinctiometers) as well as other instruments
for measurements of the surface weather condition, for launching radiosoundes,
and a small UAV to do vertical profiles of black carbon concentration in the lower
atmosphere. Instruments listed previously are easily transported from one station
to the other. Data collected at both stations are preprocessing and visualizing
within the Poland-AOD network at webpage www.polandaod.pl.
Wednesday, 11 June, 09:00 – 10:00
09:00-10:00 ACTRIS-2
Presentation of the project & discussion (part I)
G. Pappalardo / P. Laj
Oral session S2: Scientific results from ACTRIS TNA campaigns
Wednesday, 11 June, 10:00 – 12:00
Chairs: Adolfo Comerón, Sabine Philippin
S2.O1 (10:00-10:15) IDEAL-DREAM: integration of EARLINET/ACTRIS lidar observations and DREAM
dust model
L. Mona, A. Vukovic, I. Binietoglou, M. Vujadinovic, S. Nickovic3, G. Pejanovic, B.
Cvetkovic, M. Djordjevic, G. D’Amico, F. Madonna, N. Papagiannopoulos, M.
Rosoldi, G. Pappalardo
Passive ground-based (e.g., AERONET) or space-borne observations (e.g. MODIS,
MISR or OMI) have been extensively used to evaluate the 2D distribution of
particles, however the vertical distribution cannot be evaluated using these
observations. The vertical distribution of aerosol is of particular importance
because it is a combined signature of atmospheric transport patterns, residence
times in the atmosphere, and the efficiency of the vertical exchange. Lidar
techniques provides information about aerosol layering in the vertical range and
vertical profiles of aerosol optical properties.
A systematic long-term comparison of dust profiles from EARLINET stations and
the coupled atmospheric-dust model NMM-DREAM is performed for evaluating
the model vertical profiling capability. The most recent DREAM version, which
runs operationally at SEEVCCC of the Serbian Hydrometeorological Service, is used
for historical long-term simulations.
This model version also includes, in addition to dust concentration as a tracer,
fractions of major mineral groups’ characteristic for specific Saharan desert parts
(East-West), as well (Nickovic et al, 2012; Nickovic et l, 2013). These modeled
data are used for the evaluation and integration to EARLINET data. Therefore, for
selected cases with increased dust transport from Sahara to Europe, and
available lidar observations, special modeling tests will be done. Lidar data will be
assimilated into the dust concentration initial field for the dust forecast, and the
quality of forecast will be compared with regular model set-up.
The TNA access to CIAO started the collaboration between DREAM modeling
group from Belgrade and CIAO lidar group from Potenza, and enabled future
work on improving quality of dust forecast using lidar observations. Further
analysis about lidar data assimilation and ice nucleation in presence of Saharan
17
dust events will be carried out.
S2.O2 (10:15-10:30) Study of aerosol hygroscopic growth events over the CESAR (Cabauw
Experimental Site for Atmospheric Research) station by means of the Caeli lidar
A. J. Fernández, A. Apituley, F. Molero, M. Pujadas, B. Artíñano, J. Henzing and H.
Russchenberg
According to the Fifth Assessment Report (AR5) of the IPCC (2013), atmospheric
aerosols still represent the largest source of uncertainty in the total radiative
forcing estimates of the atmosphere, in particular concerning the influence of
aerosols on cloud formation processes. The so-called cloud adjustments due to
aerosols is quantified in -0.55 W m-2 (-1.33 to -0.06). Since multiwavelength
Raman lidars have the potential to provide aerosol optical properties, water
vapor mixing ratio and temperature profiles (depending on its configuration) with
high resolution in time and vertical dimensions, lidar techniques represent a
powerful tool to study these phenomena. Given the fact that Caeli (the CESAR
Water Vapour, Aerosol and Cloud lidar), deployed since 2008 at the Cabauw
Experimental Site for Atmospheric Research (CESAR) in the Netherlands (51º 58’N,
4º56’E), has been routinely performed for EARLINET purposes, the project ACIRL
(Aerosol Cloud Interaction and Raman Lidar), which has been carried out under a
Transnational Access Activity from ACTRIS, was partially devoted to identify
aerosol hygroscopic growth events from the Caeli lidar database and analyze
them thoroughly. The primary objective of this analysis is to characterize the
enhancement factor experienced by the hygroscopic aerosol throughout the
atmospheric column placed over the CESAR station. Other optical properties such
as lidar ratio and β- Ångström exponent are also considered in the case studies
that will be presented as they can be used as tracers when the water uptake
phenomenon takes place. Additionally, meteorological information is taken into
account in order to check that a well-mixed boundary layer exists and therefore
misleading results are avoided. Acknowledgments: The research leading to these
results has received funding from the EU 7th Framework Programme (ACTRIS
project, grant agreement nº 262254, and TNAs) and from the MICINN (Spanish
Ministry of Science and Innovation) under project CGL2010-17777.
10:30-11:00 Coffee break
S2.O3 (11:00-11:15) The Fourier-Transform Infrared Measurements at Maïdo and the Results of the
ACTRIS TNA Missions
F. Desmet, B. Langerock, C. Vigouroux, N. Kumps, C. Hermans, M. De Mazière, J.-
M. Metzger, J.-P. Cammas
The Belgian Institute for Space Aeronomy (BIRA-IASB) has been performing FTIR
measurements at Reunion Island since 2002, initially as part of short-term
campaigns, but since 2009 on a permanent basis. The FTIR instruments record
solar-absorption spectra of the atmosphere, from which the total column
abundance and vertical distribution of a wide variety of atmospheric species can
be retrieved. BIRA-IASB currently operates two spectrometers on the Island, one
at sea-level in St. Denis and a second instrument in the Maïdo observatory. Part
of the installation of the instrument at Maïdo and related scientific work has been
supported by ACTRIS TNA grants. The FTIR instrument on Maïdo began its
measurements in March 2013, it contributes data principally to the Network for
the Detection of Atmospheric Composition Change (NDACC).
In this presentation, we give an overview of the FTIR instruments at Reunion
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Island. We look at the benefits of the high-altitude location of Maïdo, and the
effects of the reduced interference of water vapour on the spectra and the
retrievals. We will also report our preliminary results of how the 2 km altitude
difference between Maïdo and St. Denis affects the results of the retrievals.
S2.O4 (11:15-11:30) AERONET-EUROPE TNA
P. Goloub, V. Cachorro, E. Cuevas, C. Toledano, L. Blarel, T. Podvin, R. González, C.
Guirado, A. Lapyonak
AERONET-EUROPE Trans National Access has provided, since the beginning of
ACTRIS, calibration, maintenance and technical support to CIMEL sunphotometers
belonging to various European research teams and other groups in Africa and
Asia involved in aerosols studies. This activity relies on France (LOA) and Spain
(GOA and Izaña-AEMET). We will present the main contributions and projects
supported during the second period such as number of access unit provided,
quality assurance, contribution to satellite and models evaluations, impact on the
development of synergetic use of LIDAR and sun/lunar photometer, impacts on
SMEs developments.
S2.O5 (11:30-11:45)
A source origin and physico-chemical properties of ambient Particulate Matter
studied by Stable Isotope Ratio Mass Spectrometry
A. Masalaite, D. Ceburnis, J. Ovadnevaite, V. Remeikis and C.D. O’Dowd
Carbonaceous aerosols reflect the isotope signature of their source precursors
(e.g., biogenic marine, terrestrial and fossil fuel carbon) and, consequently, their
δ13C value can be used as an indicator of the specific source. Similarly, isotopes
of sulphur and nitrogen can help to further apportion between biogenic and
anthropogenic sources.Combining the knowledge of marine aerosol properties
through the use of advanced High Resolution Time-of-Flight aerosol mass
spectrometer (AMS) with stable Isotope Ratio Mass Spectrometry (IRMS) provide
unique insight into particulate matter sources, especially when applying multi-
isotope (S, N, C) approach. High time resolution of AMS allows quantifying total
amount of carbonaceous or sulphurous components in uniquely classified marine
air masses: marine polar, marine tropical and marine arctic. Active sector control
sampling system allows apportionment of sources in the above air mass
categories by IRMS. The sampling in carefully screened marine air masses has
been initiated during an ACTRIS TNA visit and is still continuing. A method
development for multi-isotope analysis is on-going. A split between total carbon
and organic carbon δ13C in marine aerosol samples has been attempted for the
first time. The obtained results so far reaffirm previously published results of
marine carbonaceous matter enriched in heavier isotope. Parallel sampling of
size-segregated particulate matter at various locations in Lithuania helped to
further develop stable carbon isotope method in distinguishing between fossil fuel
and terrestrial source without the need of radiocarbon analysis. The samples
obtained during ACTRIS TNA visit will help to better interpret the results from
marine location in Lithuania which is significantly affected by anthropogenic
emissions en-route from the North Atlantic Ocean.
S2.O6 (11:45-12:00) Nitrogen intensive at Auchencorth Moss: Basis for study and first insights
M.M. Twigg, J. Kentisbeer, M. Coyle, S.R. Leeson, Y.S. Tang, M.R. Jones, B.
Langford, C. DiMarco, I. Simmons, I. Washbourne, M. Vieno, C.F. Braban, E.
Nemitz,W. Bloss, E. Aruffo, P. Di Carlo
19
Auchencorth Moss has been an EMEP supersite since June 2006, where currently
routinely speciated N measurements are: HNO3, NO2, NO, HONO, NH3 in gas
phase and particulate NH4+ and NO3-. It is understood that the full speciated N-
budget is currently unknown and recent studies have shown the importance of
chemical species such as trimethlyamines, PANs, ClNO2 and N2O5 at background
sites. In order to better understand the chemical climate at Auchencorth and in
particular quantify the N-speciation in the atmosphere over time and the co-
variation of non-routinely measured species against the rountine measurement,
CEH are hosting an intensive experiment to monitor nitrogen chemical speciation
over the Spring 2014 season. The spring has been chosen as the data records
show that the site frequently experiences pollution events from agricultural
activities and long range transport from continental Europe during this period.
As well as the routine measurements at Auchencorth Moss, VOC fluxes by PTRMS
and fluxes of water soluble aerosols and their precursor gases using a GRAEGOR,
the Thermal Dissociation Laser Induced Fluorescence (TD-LIF) instrument from the
Univeristy L’Aquila is deployed for simultaneous measurements of NO2, total
peroxy nitrates (∑RO2NO2, ∑PNs), total alkyl nitrates (∑RONO2, ∑ANs) and
NOy/HNO3 ,a LOPAP for HONO and a cavity ring down instrument for NH3 are
deployed to be operational through May and June 2014. The TD-LIF, in parallel
with the other systems installed at the Auchencorth moss Supersite can
contribute to understand the nitrogen oxides chemistry of the lower troposphere
and potentially quantify the budget of NOy of this site.
Poster session P2: Scientific results from ACTRIS TNA campaigns
Wednesday, 11 June, 10:30 – 11:00 and 12:00 – 12:30
P2.1 Side-by-side Intercomparison for OVOC in the framework of ACTRIS NA4
J. Englert, C. Plass-Dülmer, A. Werner and ACTRIS partners
Oxygenated volatile organic compounds are difficult to measure in atmospheric
samples due to their low mixing ratios in the low ppt to ppb range, their polarity
and associated stickiness to surfaces, and their partly high water solubility. Thus,
it is not amazing that occasionally colocated instruments with “similar”
measurement technique obtain considerably different results. With focus on high-
quality measurements, the need of a better characterisation of measurement
techniques has been identified in GAW VOC Expert meetings. This has been
addressed in the tasks of work package NA4 (Trace gases networking: Volatile
organic carbon and nitrogen oxides).
Seven groups with ten different state-of-the-art OVOC instruments (PTR-MS,
GC/MS/FID, adsorbent tube sampler and DNPH cartridges) joined in a combined
field and laboratory intercomparison exercise at the Hohenpeissenberg
Meteorological Observatory in October 2013. All instruments were connected to a
single manifold which was fed with synthetic air mixtures, zero air, pure and
spiked ambient air at controlled ozone and humidity levels. Three of the
participating groups performed TNA projects and received T&S support by
ACTRIS.
Compared to a previous intercomparison at the SAPHIR chamber in Juelich (Apel
et al., 2008), the Hohenpeissenberg OVOC intercomparison expanded the range
20
of tested mixing ratios down to the low ppt range and included synthetic and
ambient air at OVOC mixing ratios of mostly below 1 ppb, for many compounds
even below 100 ppt. Thus, it comprised a test of the instruments under typical
clean air conditions encountered at the stations of the monitoring networks of
GAW and EMEP and enables a full characterization of the detection limits, linear
ranges, and of potential artefacts due to interfering gases.
A first look at the mixing ratios obtained during the campaign indicates both
consistent results between different instruments albeit using different techniques,
and partly clear deviations of individual or groups of instruments. These
deviations are further analysed with respect to reference concentrations,
characteristics of the respective techniques, blank and calibration issues and
uncertainties. Apel, E. C. et al. (2008) Intercomparison of oxygenated volatile
compound measurements at the SAPHIR atmosphere simulation chamber, J.
Geophys. Res., 113, D20307, doi:10.1029/2008JD009865.
P2.2 Experimental assessment of the lidar polarizing sensitivity in lidar
depolarization studies for aerosol typing
Belegante L., Bravo-Aranda J. A., Freudenthaler V., Nicolae D., Alados-Arboledas
A., Amodeo A., Engelmann R., Kokkalis P., Papayannis A., and Wandinger U.
Profiles of the particle depolarization ratios retrieved from lidar data are
generally used for aerosol typing, accounting for the non-sphericity of the
particles. The particle depolarization ratio is one of the primary parameters that
can differentiate several major aerosol components, but for this the associated
uncertainties have to be sufficiently reasonable and correctly assessed. The paper
presents an extended analysis of different depolarization calibration procedures
and experimental procedures aiming to correct for the contribution of several
optical modules in the depolarization values. All procedures are specific to the
requirements of each lidar systems in the EARLINET framework, aiming to better
quantify the particle depolarization ratio. The results illustrate a significant
improvement of the depolarization lidar products for all selected lidar stations in
the network. The calibrated particle depolarization profiles show values reaching
up to 0.45±0.02 in ice crystals, 0.3±0.02 for aged dust and 0.05±0.01 for industrial
pollution aerosol. In the aerosol free regions, the particle depolarization ratio
goes down to 0.00.
Keywords: Atmospheric studies, Aerosol typing, EARLINET, depolarization
calibration, particle depolarization ratio
Acknowledgements: This work was supported by the European Community's FP7-
INFRASTRUCTURES-2010-1 under grant no. 262254 – ACTRIS and by a grant of
the STAR–ESA Programme 39/2012-SIAFIM.
P2.3 Size-dependent particle activation properties in fog during the ParisFog
2012/13 field campaign
E. Hammer, M. Gysel, G. C. Roberts, T. Elias, J. Hofer, C. R. Hoyle, N. Bukowiecki,
J.-C. Dupont, F. Burnet, U. Baltensperger and E. Weingartner
A custom built (TROPOS type) scanning mobility particle sizer (SMPS) was used
covering size ranges from 8 to 848 nm. Throughout the measuring period the
median number concentration of aerosol particles (total) was found to be 2098±
1332 cm -3. A clear annual circle with maximum concentrations during summer
and minimum during winter was observed. Both Aitken and accumulation mode
21
particles presented similar seasonality and contributed equally to the total
number. Nucleation mode presented different pattern from the other two modes,
with the highest concentrations during winter (and March), mainly during new
particle formation events that were more frequently observed during March and
October. During summer, new particle formation events were less frequent and
unimodal distributions centering in the accumulation mode size range were
dominant reflecting the dry season characteristics. When precipitation had
affected air masses arriving at Finokalia, the size distributions were bimodal,
typical for marine origin, and representative of the background marine conditions
at Finokalia.
P2.4 Ceilometer for aerosol profiling: comparison with the multiwavelength in the
frame of INTERACT (INTERcomparison of Aerosol and Cloud Tracking)
F. Madonna, J. Vande Hey, F. Amato, M. Rosoldi, G. Pappalardo.
Observations of cloud base height are important for meteorology, observations of
aerosols are important for air quality applications, observations of cloud cover
and aerosols address key uncertainties in climate study. To improve
parameterization and uncertainties of numerical models, observations provided
by high resolution networks of ground-based instruments are needed. In order to
achieve broad, high resolution coverage, low-cost instruments are preferable,
though it is essential that the sensitivity, stability, biases and uncertainties of
these instruments are well-understood.
Despite of their differences from more advanced and more powerful lidars, low
construction and operation cost of ceilometer, originally designed for cloud base
height monitoring, has fostered their use for the quantitative study of aerosol
properties. The large number of ceilometers available worldwide represent a
strong motivation to investigate to which extent they can be used to fill the
geographical gaps between advanced lidar stations and how their continuous
data flow can be linked to existing networks of the advanced lidars, like EARLINET
(European Aerosol research LIdar NETwork).
In order to make the best use of existing and future ceilometer deployments,
ceilometer must be better characterized. This is the purpose of the INTERACT
campaign carried out in the frame of ACTRIS Transnational Access activities at
CNR-IMAA Atmospheric Observatory (CIAO - 760 m a.s.l., 40.60 N, 15.72 E).
The scientific objectives of INTERACT are to evaluate the stability, sensitivity, and
uncertainties of ceilometer aerosol backscatter profiles and to evaluate the
sensitivity, uncertainties, and idiosyncrasies of ceilometer automated cloud base
detection. In the frame of INTERACT, for the first time, three commercial
ceilometers from different manufactures have been compared with an advanced
Raman lidar.
INTERACT data collection began officially on 1 July, 2013 and ended on 10
January, 2014. The ceilometers run 24-7, reporting at least once per minute.
Multi-wavelength Raman lidar measurements performed at CIAO Atmospheric
Observatory (760 m a.s.l., 40.60 N, 15.72 E), performed on a systematic basis (at
least four times a week) have been used to investigate the capability of
ceilometers to provide reliable information about the atmospheric aerosol
content.
The study of the attenuated backscattering values as a function of both the
altitude and the 355 nm aerosol extinction coefficient (α), provided by the multi-
wavelength Raman lidar, reveals a few limitations both in the ceilometer
22
experimental setup and in the achieved SNR. Further technological improvements
of the ceilometers towards their operational use in the monitoring of the
atmospheric aerosol looks mandatory.
P2.5 ACTRIS Trans National Activities at the SIRTA Atmospheric Observatory (2011-
2014)
M. Haeffelin, J-C. Dupont, C. Pietras; J. Sciare, V. Gros
The SIRTA observatory gathers an ensemble of state-of-the-art in-situ and active
and passive remote sensing instruments deployed by several French research
laboratories since 2002 for cloud, aerosol and trace gas research. In the 2011-
2014 timeframe, SIRTA hosted 5 transnational activity projects in the framework
of ACTRIS, providing a total of 260 access days. Four TNA project took place in the
framework of international field campaigns organized at the SIRTA observatory,
providing both mobility of experts and training benefits. The fifth project was
hosted to provide training benefits. Project 1 (2011) focused on comparison of OH
and OH reactivity measurements made with different techniques. 37 ACTRIS TNA
access days were provided to 3 users, while 140 other access days were also
provided to 5 other user groups during the same campaign. Projects 2 and 3
(2012-2013) were organized as part of the ParisFog international field
experiment. The ParisFog campaign gathered 6 user groups over a period of 6
months from October 2012 to March 2013. Project 2 focused on understanding
aerosol activation during radiative fog events under moderately polluted
conditions (50 access days, 2 users incl. 1 PhD student). Project 3 aimed at better
characterizing turbulent fluxes of fog droplets/liquid water by using the eddy
covariance techniques (138 access days, 4 users incl. 2 PhD students). Both TNA
projects resulted in scientific publications. Project 4 took place in the framework
of an ACTRIS international Aerosol Chemical Speciation Monitor intercomparison
campaign (8 access days, 1 user). The campaign gathered 14 user groups during 3
weeks in November 2013. Project 5 will allow two users from Bulgaria, including 1
PhD student, to conduct a study on aerosols and turbulence as tracers of the
diurnal evolution of boundary layer height. It will take place in May 2014. Results
from the 5 projects will be presented, and highlights from other non-ACTRIS user
accesses to the facility will also be provided.
P2.6 QA /QC of European NOx measurements by round robin and side by side
experiment at the Meteorological Observatory Hohenpeissenberg in the
framework of ACTRIS
Stefan Gilge, Christian Plass-Duelmer, Dietmar Weyrauch, Franz Rohrer and the
ACTRIS-NOx-Team.
The European ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure
Network) project, Work Package 4, aims at harmonization and improvement of
the measurement of volatile organic carbons and nitrogen oxides. Central tools to
assess and compare the performance of monitoring stations and labs within
ACTRIS are a round robin experiment (2012) and side-by-side intercomparisons
(Nov 2012). While the first checked the used laboratories’ scales versus a common
scale, the latter investigated weather same samples are identically and artefact-
free analyzed by collocated instruments. The ACTRIS-NOx-side-by-side
intercomparison was realised by instruments sampling from a common manifold
which was fed by zero gas, synthetic air mixtures, ambient air, and spiked
ambient air. Thus, the side-by-side experiments enabled a full characterization of
23
the detection limit, the linear range, the span, and of potential artefacts due to
interfering species for each of the contributing instrument. Generally, CLD type
NOx instruments were used in the comparisons supplemented by four new optical
techniques, comprising LIF and cavity enhanced techniques. In the round robin
exercise, some 20 monitoring sites participated, and 14 instruments were running
side-by-side in the one week Nov comparison. The results of both experiments will
be presented and discussed with respect to the data quality objectives of GAW
and ACTRIS.
P2.7 Feedbacks between Turbulent Fluxes of Heat, Water Vapor and Liquid Water
and Droplet Microphysics in the evolution of Radiation fog at SIRTA, France
Degefie Tibebe, Otto Klemm, Tarek El-Madany and Jean-Charles Dupont
The interaction between fog microphysical properties and turbulent fluxes of fog
droplets (liquid water), water vapor, and energy was studied based on the
measurement made during the PARISFOG campaign in winter 2012/2013 at the
SIRTA (Site Instrumental de Recherche par Télédétection Atmosphérique)
atmospheric observatory near Paris. The measurement was undertaken using the
eddy covariance technique employing a fast (10 Hz) fog droplet spectrometer, a
three-dimensional ultrasonic anemometer, and a fast response gas analyzer,
which were operated at an altitude of 2.5 m above ground. Additionally, a
visibility meter was used to detect the occurrence and density of fog. In this study,
a detailed analysis was made on one of the radiation fog events which happened
on November 8-9, 2012. In the evolution of the fog event, the feedbacks between
the microphysical properties and the turbulent fluxes of fog droplets (liquid
water), water vapor and energy was examined with the combined reasoning of
microphysical processes like condensation, collision–coalescence, and droplet
evaporation. Both upward and downward droplet number fluxes and liquid water
fluxes were observed depending on the position at which the microphysical
process occurred with respect to the measurement height. The downward water
vapor fluxes were the major cause for (I) the broadening of the fog droplet size
distribution and (II) the largest upward fog water fluxes throughout the whole
event.
P2.8 Understanding aerosols as tracers of boundary layer development and
turbulence mixing processes
M. Haeffelin, J-C. Dupont, (IPSL/CNRS); E. Batchvarova, O. Gueorguiev (NIMH); S.
Pal (U. of Virginia); N. Cimini (CNR-IMAA)
The development of the boundary layer in convective conditions, and the depth of
the layer in which surface emitted constituents are mixed, must be well
understood to relate fluxes and concentrations. Air pollution and greenhouse gas
communities are interested in precisely tracing the mixing depth to improve
predictions of atmospheric constituents such as fine-mode aerosols or CO2.
Vertical profiles of several tracers and parameters can be used to define the
mixing layer depth, such as the potential temperature, water vapor mixing ratio,
wind variance, aerosol concentration or extinction coefficient. Retrieving the
mixing depth then requires instruments that can provide vertical profiles of these
parameters, preferably several times per day to cover mixing depth variations in
the diurnal timescale. Well-known candidates are aerosol backscatter profiles
from ground-based lidars, vertical velocity variance profiles from Doppler lidar,
potential temperature profiles from microwave radiometers (MWRs) and
24
radiosondes, temperature turbulence profiles from sodars.
In this presentation we will focus on analyses of discrepancies of mixing height
retrievals from aerosol backscatter Lidar, wind variance from Doppler Lidar and
temperature profiles from microwave radiometers. We will aim at identifying and
describing physical processes that can explain discrepancies between retrievals
based on aerosol profiles and those based on potential temperature profiles and
wind velocity variance.
12:30-14:00 Lunch break
Oral session S3: ACTRIS integration activities
Wednesday, 11 June, 14:00-17:00
Chairs: Philippe Goloub, Markku Kulmala
Keynote presentation
(14:00-14:30)
Aerosol_CCI validation experiences
Thomas Holzer-Popp (DLR, Germany)
S3.O1 (14:30-14:45) Aerosol typing based on 24/7 measurements with EARLINET multi-wavelength-depolarization lidars in analogy to Cloudnet H. Baars, P. Seifert, F. Schneider, R. Engelmann, and U. Wandinger
An automatic technique for the classification of different aerosol types from
EARLINET measurements was developed in the frame of ACTRIS. This
development is a synergistic approach to the Cloudnet cloud classification scheme
which makes use of ceilometer, radar, and microwave radiometer but provides no
sophisticated aerosol information. The new retrieval scheme is based on
continuous observations with multi-wavelength-depolarization Raman lidars.
Developments within EARLINET/ACTRIS concerning quality assurance and
calibration made it possible to develop hardware tools to run the lidar systems
quality-controlled in a 24/7 mode.
In this contribution, the procedure for aerosol retrievals is described in terms of
hard- and software for the example of the PollyXT lidar which is operated by
TROPOS, Leipzig, Germany. For the particle classification, the backscatter profiles
at three wavelengths are used to detect aerosol and cloud layers and to
distinguish between those two. Simple thresholds are used to separate liquid
clouds from other features. For aerosol and ice clouds, the classification is much
more sophisticated and makes use of the intensive particle properties. For this
purpose, the Ångström exponent is used as a rough measure of the particle size
and the depolarization ratio is used to determine the particle shape. The
knowledge gathered from the long-term observations within EARLINET is finally
applied for the target classification which distinguishes between the following
features: clean atmosphere (no particles); small aerosol particles (e.g., urban
pollution); large, spherical aerosol particles (e.g., marine); aerosol mixture (partly
non-spherical particles, e.g., polluted dust); large non-spherical particles (e.g.,
dust or volcanic ash); non-typed particles; ice clouds; liquid clouds; and non-typed
clouds.
In this contribution, examples of the typing from PollyXT measurements will be
shown and compared to the corresponding Cloudnet classification. For future
25
applications, the combination of this lidar stand-alone retrieval with the Cloudnet
target categorization will be discussed to make full use of the synergy of the
available instruments.
S3.O2 (14:45-15:00) Framework for monitoring aerosol-cloud interactions K. Sarna and H.W.J. Russchenberg
A broad range of strategies have been used to study the first aerosol indirect
effect [2]. However, the wide scope of methods and scales used makes it difficult
to quantitatively compare result from different studies. We propose a new
approach for aerosol-cloud interaction (ACI) observations, which will provide a
fast and easily applicable way of identifying cases where a change in the aerosol
environment causes a change in the cloud. In this scheme we attempt to use (as
far as possible) the observed signal from lidar and radar, in order to bypass
the complexity and uncertainty associated with different retrieval techniques.
We propose to use the attenuated backscatter as an aerosol proxy and the radar
reflectivity factor combined with the extinction coefficient at the cloud base to
obtain information about changes in the cloud. To retrieve the extinction
coefficient we use a stable lidar profile inversion [1] with a correction for multiple
scattering effects. Together with radar reflectivity the extinction coefficient is
used to estimate the size of cloud droplets in the lower part of the cloud only. To
eliminate other factors that can change microphysical properties of the cloud we
put a constraint on the liquid water path. Although this method is based on a
synergy of remote sensing instruments, we use widely available systems for a
quick and efficient evaluation of the aerosol influence on the cloud. The main
advantages of this scheme include fast data processing and a possibility of easy
application at new or existing observational sites. Moreover, this approach
enables processing large time series of data and is less restrictive in cases
selection tan most microphysical cloud properties retrieval algorithms. We plan to
implement this framework over the cloud profiling sites of the ACTRIS network to
enable monitoring of the ACI close to real-time.
References
[1] Klett, J. D. Stable analytical inversion solution for processing lidar returns.
Appl. Opt. 20, 2 (Jan. 1981),
211–220.
[2] McComiskey, A., and Feingold, G. T
S3.O3 (15:00-15:15) On scientific breakthroughs from ACTRIS observations and on integration of ACTRIS observation components
T. Petäjä et al. + ACTRIS partners + BAECC partners + PEEX partners
Recent technological advances in aerosol measurement techniques have enabled
comprehensive analysis of chemical and physical characterization of atmospheric
nanoparticles. For example, we have underlined the importance of sulfuric acid,
bases and extremely low volatile organics to the initial clustering as well as to
aerosol growth to climatically relevant sizes (Sipilä et al. 2010, Almeida et al.
2013, Kulmala et al. 2013, Ehn et al. 2013, Riccobono et al. 2014). Within the
harmonized ACTRIS observation network we have been able put the observations
in a larger context via campaigns, partly supported by transnational access e.g. to
Hyytiälä, Jungfraujoch and Mace Head.
Co-located observations of in-situ and active remote sensing in campaigns such as
26
"Biogenic Aerosols- Effects on Clouds and Climate, BAECC" in Hyytiälä will provide
essential instrumental and methodological intercomparison as well as possibilities
for various closure studies, which are also the focus of BACCHUS project. The joint
campaign with AMF2 in BAECC as well as Pan Eurasian Experiment (PEEX) provide
extension of integrated ACTRIS data products beyond Europe.
S3.O4 (15:15-15:30) Results of the first-ever ACSM intercomparison study from the ACTRIS-ACSM network V. Crenn, J. Sciare, O. Favez, P. L. Croteau, R. Fröhlich, A. Setyan, S. Verlhac, V. Riffault, M. Äijälä, M. Bressi, C. Carbone, F. Cavalli, E. Coz, M. J. Cubison, J. K. Gietl, L. Heikkinen, C. Lunder, M. C. Minguillón, J. Ovadnevaite, E. Petralia, L. Poulain, M. Priestman, A. Ripoll, B. Artíñano, D. Baisnée, N. Bonnaire, M. Canagaratna, D. C. Green, G. Mocnik, V. Gros, J.-E. Petit, R. Sarda-Estève, J. T. Jayne, and A. S. H. Prévôt
As part of the EU-FP7 ACTRIS program, a large international intercomparison
study of 15 aerosol mass spectrometers (13 Q-ACSM, 1 ToF-ACSM and 1 HR-ToF-
AMS) has been performed from 15 Nov. to 2 Dec. 2013 at the LSCE in-situ
atmospheric platform which is part of the French SIRTA observatory
(http://sirta.ipsl.fr) located at 20km southwest of Paris. During this period, each
instrument measured the major non-refractory submicron aerosols (NR-PM1)
components (organic matter, nitrate, sulfate, and ammonium) in ambient air.
The accuracy of Q-ACSM instruments was determined by comparison with various
co-located instruments (TEOM-FDMS, SMPS, OPC, OC-EC Sunset Field analyzer,
PILS-IC, aethalometers, nephelometers, and filter sampling). The measurement
precision was also evaluated by intercomparing the correlation of absolute mass
concentrations for all the NR-PM1 species. The ACSM analytical uncertainties
were then estimated by applying a statistical approach in order to evaluate the
analytical standard deviations between ACSMs and to highlight any bias or
influencing factor on the ACSM measurements. For this purpose, the Z-score
indicator representing performance criteria was used making it possible to
measure its relative deviation to the assigned value. Fig. 1 summarizes the Z-
Score results applied to the 13 Q-ACSM datasets for the major chemical species of
the NR-PM1. All the ACSMs present satisfactory Z-Score values (a Z-Score value of
3 is considered as the limit value) whatever the considered parameter
highlighting the instrument precision.
Figure 1: Statistical Z-Score results for total NR-PM1
concentrations and their major components measured by
the 13 Q-ACSMs.
15:30-16:00 Coffee break
S3.O5 (16:00-16:15) Co-located station Košetice (ACTRIS) – Křešín u Pacova (ICOS) M. Váňa and A. Dvorská
The co-located station (geographical co-ordinates: 49°35´ N; 15°05´E; 534 m
a.s.l.) is formed by Košetice Observatory (operated by the Czech
Hydrometeorological Institute) and 250 m high atmospheric mast (operated by
Global Change Research Centre, Academy of Sciences of the Czech Republic). The
Observatory was established in 1988 as a background station specialized in air
quality monitoring and research and represents Czech Republic in long-term
activities under CLRTAP (EMEP, ICP-IM) and WMO (GAW). Tall tower was opened
in 2013. The most important research and monitoring activities include long-term
27
measurement of greenhouse gases concentrations and their exchange dynamics
under the ICOS project. The tower is also used for investigating the impacts of
global climate change on air quality and long-range transport of air pollution. The
research will be focused on pollutants with a high potential for hemispheric
transport (tropospheric ozone, aerosols and mercury). Besides ICOS and ACTRIS,
co-located station is involved in other EU projects (InGOS, GMOS). Special
attention is devoted to atmospheric aerosols which have besides greenhouse
gases an important impact on global climate change processes. The integration of
ACTRIS and ICOS activities at the core stations is in line with the ACTRIS objectives
for Integration, Outreach and Sustainability (NA6). Co-located ACTRIS – ICOS
station Košetice has very good potential for successful participation in the pan-
European Research Infrastructures (RIs) under ESFRI and other projects covering
both climate and air quality issues. Moreover, monitoring and research activities
within ACTRIS and ICOS will bring essential improvement for the Czech
partnership in long-term monitoring programmes (EMEP, GAW).
S3.O6 (16:15-16:30) Advanced Analysis of Atmospheric Processes and Feedbacks and Atmosphere-Biosphere Interactions
Markku Kulmala
Quantification of feedbacks and relationships between atmosphere and biosphere
using a variety of relevant datasets from several measurement stations. Results
from ACTRIS winter school, Hyytiälä 2014
S3.O7 (16:30-16:45) ACTRIS Data Centre: Description and demonstrations by active user participation Cathrine Lund Myhre, Thomas Hamburger, Robert Logna, Markus Fiebig, Aasmund Fahre Vik Holger Linné, Ewan O'Connor, Kjetil Tørseth
The ACTRIS data centre (ACTRIS DC) provides free and open access to all
measurement data resulting from the ACTRIS infrastructure. This includes
currently measurements from more than 50 sites and of approximately 120
different atmospheric variables, 90 different trace gases, 10 aerosol in situ
variables, 10 aerosols profile variables, and 8 cloud variables. After careful and
systematic quality assurance, all observational data are archived in three
specified databases, depending on measurement type and methodology. The
ACTRIS data portal links these databases and provides joint overview and access
to all ACTRIS data from one location (http://actris.nilu.no/). The ACTRIS data
portal is complemented with data from other relevant networks and databases,
and allows users to search for atmospheric composition data from a multitude of
data archives through a single user interface. Some of the included frameworks
are EMEP, the GAW- world data centres, EARLINET, NDACC, and AMAP. All data
from e.g. EMEP and NDACC can be downloaded through the ACTRIS data portal.
The portal is currently under revision, and new functionality gets implemented
during spring 2014. This development includes an improved user interface,
plotting functionality for comparing and integrating data across various ACTRIS
activities, improved interface to AEROCOM, access to ACTRIS Standard Operating
Procedures (SOPs), and improvement of data format and meta data descriptions.
During the poster session at the 4th ACTRIS meeting we will demonstrate and
explain the ACTRIS data portal. We plan to set up PCs to actively involve ACTRIS
28
data users and partners, to assist and demonstrate the use of the ACTRIS data
portal. This activity will also facilitate the collection of feedback for final
adjustments within the ACTRIS project. Furthermore, we will provide an overview
of all sites delivering data to ACTRIS, and summarize the access to measurements
within the ACTRIS project.
S3.O8 (16:45-17:00) Proposal for the integration of ACTRIS Near-Real-Time NO2 data in the evaluation activities of the Copernicus Atmosphere Service (MACC-II) Annette Wagner, Harald Flentje, Stefan Gilge, Werner Thomas and the MACC Team
The MACC-II (Monitoring Atmospheric Composition and Climate- phase II) project
is the current pre-operational Atmosphere Service of the European earth
observation program Copernicus. MACC-II combines state-of-the-art atmospheric
modelling with earth observation data to provide information services covering
European air quality, global atmospheric composition, climate forcing, the ozone
layer, UV and solar energy, emissions and surface fluxes in Near-Real-Time. The
sub group “VAL” of the MACC-II project is focusing on the evaluation of modelled
reactive gases, such as stratospheric and tropospheric ozone as well as its
precursors and aerosols in the global ECMWF integrated forecasting system IFS.
Currently, GAW NRT data of 13 stations is used to validate modelled O3 and CO
surface mixing ratios globally. Additionally, ozone sonde data of the NDACC,
WOUDC, NILU and SHADOZ networks enable a validation of O3 profiles.
Here, we will give an overview on the Near-Real-Time (NRT) evaluation activities
in MACC and an outlook on a potential use of ACTRIS NO2 NRT data in the
evaluation activities of the Copernicus Atmosphere Service.
17:00 Excursion to the Puy de Dôme and social dinner (return ~23:30)
Oral session S4: ACTRIS, Model and Satellite
Thursday, 12 June, 9:00 – 10:30
Chairs: Stefan Reimann, Ulla Wandinger
Keynote presentation
(9:00-9:30)
ICOS-ACTRIS Synergies Werner Kutsch (ICOS, EU)
S4.O1 (9:30-9:45) Aerosol-Cloud interactions over the Nordic countries
Moa Sporre, Erik Swietlicki, Paul Glantz and Markku Kulmala
One of the major uncertainties in predicting the future climate is aerosol-cloud
interactions. 10 years of satellite data of clouds from the MODIS (Moderate
Resolution Imaging Spectroradiometer) instrument has been combined with
ground-based aerosol measurements from two Nordic ACTRIS stations (Vavihill
and Hyytiälä). This is done to investigate how aerosols affect cloud properties of
convective and low-level clouds. Furthermore, to determine if precipitation is
affected by aerosol particle number concentrations, weather-radar data from the
Baltic Sea Experiment has been used. Reanalysis data from the European Centre
for Medium-Range Forecasts is also investigated to determine how
meteorological conditions affect the aerosol-cloud interactions. This study is an
example of how multiple long-term data sets are combined to elucidate complex
29
aerosol-climate interactions.
Increasing aerosol number concentration of aerosol particles are found to be
associated with decreasing droplet sizes for both convective (Sporre et al., 2014a)
and low-level clouds (Sporre et al., 2014b). The cloud optical thickness is however
not found to be affected by the aerosol number concentrations for either cloud
type. This implies that no first indirect aerosol effect can be detected in these
clouds. The precipitation intensity is nevertheless found to decrease in air-masses
with higher aerosol number concentrations for both the convective and low-level
clouds and hence the second indirect aerosol effect is detected in these datasets.
The meteorological conditions are found to affect the clouds but not the aerosol-
cloud relationships.
S4.O2 (9:45-10:00) Biogenic SOA formation in the subarctic – Comparison between process models of varying complexity E. Hermansson, P. Roldin, A. Rusanen, D. Mogensen, N. Kivekäs, M. Boy and E. Swietlicki (A. Kristensson)
Biogenic volatile organic compounds (BVOCs) emitted by the vegetation play an
important role for the aerosol mass loadings since the oxidation products of these
compounds can take part in the formation and growth of secondary organic
aerosols (SOA). The concentrations and properties of BVOCs and their oxidation
products are poorly characterized, which lead to high uncertainties in modeled
SOA mass and properties.
The aim of this study is to investigate the effect that different gas phase oxidation
schemes have on the modeled evolution of SOA at atmospheric conditions. SOA
formation is modeled along an air mass trajectory over the northern European
boreal forest, passing three measurement sites: Abisko, Pallas and Värriö, using
two aerosol dynamics box models. Both models are coupled to the near-explicit
Master Chemical Mechanism version 3.2 (MCMv3.2) which is used when
predicting the oxidation products of the BVOCs. This near-explicit treatment of
organic gas-phase oxidation was compared to different oxidation schemes that
use the volatility basis set (VBS) approach, in order to get an indication of the
uncertainties and importance of different processes in the VBS regarding SOA
formation.
The result of the study shows that the modeled mass concentration of SOA is
highly dependent on the organic oxidation scheme used to predict the oxidation
products. The resulting SOA mass modeled with different VBS-schemes varies by a
factor of about 7 depending on how the first generation oxidation products are
parameterized and how they subsequently age. Since the VBS approach is
frequently used in regional and global climate models due to its relatively simple
treatment of the oxidation products compared to near-explicit oxidation schemes,
a better
understanding of the abovementioned processes are needed. The use of box
model simulations can indicate which processes that need to be further studied in
order to parameterize them better.
S4.O3 (10:00-10:15) Consistency of aerosol trends using ACTRIS data together with AeroCom, EMEP and MACC model data
Michael Schulz, Jan Griesfeller, Hilde Fagerli, Svetlana Tsyro, Paul Eckhardt,
Cathrine Lund Myhre, Markus Fiebig, Wenche Aas
Aerosol trends in Europe after 1990 show a significant shift in composition due to
30
the reduction in sulphate content. Nitrate should have been reduced as well
according to emission inventories. Such shift in composition should be reflected in
several aerosol parameters, from optical properties to aerosol size and
composition. We investigate here with the help of consistent model simulations
from AeroCom, EMEP and MACC how consistent such trends are with observed
data, including those from ACTRIS. The work makes extensive use of the
EBAS/ACTRIS data center and a new feature of the AeroCom web interface
showing specific ACTRIS related model/data comparisons.
S4.O4 (10:15-10:30) Organic aerosol global model evaluation, process understanding and source attribution based on ACTRIS/EUSAAR observations Maria Kanakidou et al. (N. Mihalopoulos)
The use of EUSAAR/ACTRIS OC data for the OA AEROCOM intercomparison
exercise (Tsigaridis et al ACPD, 2014) and our plans to further use ACTRIS data for
model evaluation and source understanding. This includes the current status of
global modeling of the organic aerosol (OA) in the troposphere and analyze the
differences between models as well as between models and observations.
10:30-11:00 Coffee break
Oral session S1b: Scientific achievements at ACTRIS stations
Thursday, 12 June, 11:00 – 12:00
Chairs: Paolo Laj, Michael Schulz S1.O9 (11:00-11:15) Mineral dust aerosols from the Sahara desert over Moussala in the period 2011
and 2013
Assen Tchorbadjieff, Ivo Kalapov
The Basic Environmental Observatory (BEO) at Moussala is the only operational
high mountain observatory for real time monitoring of high altitude aerosols in
South-East Europe. It is separated from Sahara desert only by Mediterranean and
it is very common to be on the way of air masses transport from the desert,
usually in spring and early summer. The frequency and intensity of air masses
with Sahara origin are random with different impact on clouds, atmospheric
dynamics and chemistry, air quality, and biogeochemical cycles in the region.
They are mainly with rare concentrations of minerals. However, it was observed a
number of very strong events not only in the region of Moussala, but in the
nearby territory. This paper summarizes recent progress on monitoring and
analysing the dust detection from the Sahara based on measurements performed
on Moussala. The data is compared with a relative satellite sources and available
LIDAR observation in Sofia, the city located in about 50 km away from Moussala.
S1.O10 (11:15-11:30) C2H6, NO2 and HCHO measurements at the high-altitude alpine station of Jungfraujoch (46.5°N, 8.0°E) B. Dils, F. Hendrick, J. Cui, B. Franco, D. Helmig, S. Henne, C. Hoerger, J. Hueber, E. Mahieu, J.-F. Müller, S. Reimann, T. Seitz, M. Steinbacher, T. Stavrakou, R. Sussmann, M. Van Roozendael, and M. De Mazière
In this presentation, we investigate the capability of retrieving NO2 and HCHO
near-surface concentrations and tropospheric vertical column densities from
MAX-DOAS measurements at the high-altitude station of Jungfraujoch (3580m
asl) in the Swiss Alps. In the case of HCHO, our retrievals are compared to
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collocated FTIR observations, taking into account the difference in vertical
resolution between both techniques. Simulations from the 3D-CTM IMAGES are
also used to further assess the observed seasonal and diurnal cycles of HCHO
surface concentration and vertical column. Regarding NO2, retrieved near-surface
concentrations are compared to in-situ observations simultaneously performed at
the station. The difference in spatial representativeness between both data sets is
taken into account using the FLEXPART trajectory model. We also compared C2H6
in-situ with FTIR total column measurements at the Jungfraujoch station. We
were particularly interested in to what extent in situ data contains information
about the atmosphere above the station. To explore this we corrected IMAGES
model profiles with the in situ data, using various degrees of vertical impact, prior
to its comparison with FTIR data.
S1.O11 (11:30-11:45) Sources, seasonal variability and oxidation state of organic aerosol in the Eastern Mediterranean A. Bougiatioti, I. Stavroulas, E. Kostenidou, F. Canonaco, A.S.H. Prévôt, S.N. Pandis and N. Mihalopoulos
The sources, seasonal variability and oxidation state of organic aerosol were
studied at the remote background site of Finokalia, Crete (Eastern
Mediterranean) for a period of 16 months (June 2012 to December 2013). The
study is based on measurements performed using an Aerosol Chemical Speciation
Monitor (ACSM) and the resulting organic components identified by Positive
Matrix Factorization (PMF) analysis of the organic mass spectra. Different factors
and subsequently different sources are identified depending on the season, each
factor having varying contribution to the total organic aerosol (OA). Overall the
O/C ratio of the total OA varies between 0.61 and 1.31, with a mean value of
1.06±0.13, which is within the observed values of low-volatility oxygenated
organic aerosol (OOA) and dicarboxylic acids. This ratio can be a proxy for the
oxidation state and its variability can reflect the variations in OA age during the
measurement period. Based on PMF analysis, throughout the study period the
factor that exhibits the largest contribution is a highly oxygenated OA with
pronounced relative intensity of m/z 18 and 44, which is furthermore supported
by its elevated O/C (1.25±0.07). It exhibits a seasonal cycle with minimum
average concentrations during winter (1.07±0.82 μg m-3) and maximum during
summer (2.13±1.07 μg m-3) and respective contribution of 52% and 58%. Long-
range transport of biomass burning from Southeastern Europe and countries
surrounding the Black Sea influence the site during two periods (April-May and
July-September). The fresh BBOA factor during these periods is estimated to
contribute on average 17.1±2.2% to the total OA. A distinct regional source of
olive tree branches burning, which is a common agricultural waste management
practice in the Mediterranean area after the annual pruning of olive trees, is also
identified from November to February (not included in the aforementioned
BBOA). The main difference between the mass spectrum of the olive tree
branches burning and other published biomass burning spectra is the almost
equal intensities of m/z 43 and 44 and the lower intensity of m/z 60. The olive
tree burning factor can contribute up to 48% of the identified OA during
wintertime. This source can be regarded as an important emission source during
this season in Mediterranean area, as the olive tree branches burning mainly
takes place when there is no rainfall or high wind speeds, which could scavenge
the produced particulate matter.
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S1.O12 (11:45-12:00) Vertical profiles of fine-mode and coarse-mode aerosol concentrations derived from combined lidar and sunphotometer observations Ulla Wandinger, Anatoli Chaikovsky, Oleg Dubovik, Anton Lopatin, Albert Ansmann, et al.
The ACTRIS Joint Research Activity “Lidar and sunphotometer — Improved
instruments, integrated observations and combined algorithms” aims at the
development and implementation of integrated lidar and sunphotometer
inversion algorithms to obtain advanced information on aerosol microphysical
properties. Two different algorithms have been developed and tested. The first
one is the Lidar/Radiometer Inversion Code (LIRIC) created at the Institute of
Physics of the National Academy of Sciences of Belarus, Minsk. The second
algorithm is the Generalized Aerosol Retrieval from Radiometer and Lidar
Combined data (GARRLiC) developed at Laboratoire d’Optique Atmosphérique,
Lille. The concepts of these two algorithms are slightly different. Whereas LIRIC
makes use of final sunphotometer products of columnar aerosol microphysical
properties and multiwavelength lidar signals, GARRLiC starts with sun and sky
radiances measured with radiometer and performs a complete new inversion of
both radiometer and lidar data.
Both algorithms have been applied to combined EARLINET and AERONET
observations at selected stations distributed over Europe to retrieve volume and
mass concentration profiles for fine-mode and coarse-mode particles. If the
particle linear depolarization ratio is measured with lidar, also the contributions
of non-spherical and spherical scatterers can be distinguished. Thus the retrievals
allow, e.g., the separation of dust from natural source (coarse, non-spherical
particles) and anthropogenic pollution or smoke (fine particles).
The potential and limitations of the methods will be discussed based on selected
measurement cases from ACTRIS stations in the Mediterranean, Central and
Eastern Europe. Comparisons with lidar stand-alone retrievals and with in situ
observations will be presented, and an outlook for further implementation of the
algorithms in the network will be given.
Poster session P3 / P4: ACTRIS, Model and Satellite / Scientific achievements at ACTRIS
stations
Thursday, 12 June, 12:00 – 13:00 and 16:00 – 19:00
P3.1 Analysis of dust transport over Barcelona using lidar and DREAM model: some
unusual case studies
Smadar Egert, Pavel Kishcha, Michaël Sicard, Adolfo Comerón, Pinhas Alpert
The Geophysics group of Tel Aviv University (TAU) is a part of an international
project with the KIT (Karlsruhe Institute of Technology, KIT/Germany) called DEad
SEa Research Venue (DESERVE). The goal of one part of this project is to monitor
the meteorological and aerosol properties in a 10X10 km cube over the Dead Sea.
Remote atmospheric measurements and COSMO (Consortium for Small-scale
Modeling) model are the planned tools for evaluation. The TAU group performs
regularly DREAM-8 (Dust Regional Atmospheric Model) calculations of dust
transport, whose predictions are a tool to calibrate the COSMO model, which has
33
never been used over Israel. At ground level, this calibration will be performed at
high resolution using the Israeli network of PM particle measurements. In order to
calibrate the vertical profiles, DREAM-8 outputs are compared to the Universitat
Politècnica de Catalunya (UPC) lidar observations during two dust outbreaks in
Barcelona in the period 6 – 16 June 2014. Hysplit backtrajectories and sun-
photometer measurements were used to confirm the aerosol origin.
The DREAM model predicts the layer height and dust mass concentration. The
lidar-derived mass concentration profiles are calculated by dividing the measured
extinction profiles by a constant specific extinction cross section taken from
previous works at the UPC and published in the literature. It is found that in terms
of structure, DREAM-8 predictions agree quite well with the dust layer height and
thickness observed by the lidar. In terms of mass concentration, DREAM-8 always
overestimates by a factor 2 to 10 the concentration retrieved from the lidar
observations. A pattern is observed in the outcome of the comparisons between
the model and the observations: the highest the concentration difference, the
best the vertical structure agrees. In spite of the dream predictions of the dust
layer, the Hysplit predicts Saharan dust only in part of the cases. The analysis will
be presented as an interesting case and a basis for discussion for the origin of the
discrepancies found.
P3.2 Aerosol typing over Europe from ground-based lidar measurements and its
benefits for spaceborne lidar observations
Anja Schwarz, Ulla Wandinger, Ina Mattis, and the EARLINET consortium
This study shows how advanced ground-based lidar measurements of EARLINET
are used to validate lidar observations of CALIOP (Cloud-Aerosol Lidar with
Orthogonal Polarization) onboard the polar-orbiting satellite CALIPSO (Cloud-
Aerosol Lidar and Infrared Pathfinder Satellite Observations).
CALIOP is operating at 532 and 1064 nm and provides vertically resolved
information on aerosol and cloud parameters on a global scale since June 2006.
For the analysis of data obtained from this elastic-backscatter lidar, a priori
assumptions on a fixed aerosol-type-dependent lidar ratio (extinction-to-
backscatter ratio) are required in order to derive the particle extinction coefficient
and thus the aerosol optical thickness. In contrast, advanced ground-based lidars
provide the aerosol backscatter and extinction coefficients independently and at
multiple wavelengths as a function of aerosol type.
For the present study, EARLINET data obtained during the ESA-CALIPSO project
(EARLINET’s Spaceborne-related Activity during the CALIPSO mission), funded by
the European Space Agency, are used. These ground-based observations were
performed in correlation to CALIPSO overpasses based on a sophisticated
measurement schedule. Aerosol optical properties were evaluated in detail and
compared to the output of the automated CALIPSO data retrieval algorithms
based on a critical assessment of the implemented aerosol classification scheme.
Results of the comparisons are shown.
The performed study is also a valuable basis for future lidar measurements from
space. The ADM–Aeolus and EarthCARE missions will continue and extend
spaceborne lidar observations. For these missions 355-nm high-spectral-
resolution lidars will be applied. To relate data from the different sensors and to
harmonize continuous global observations of aerosol properties from space a
statistical evaluation of aerosol optical properties obtained from EARLINET
34
measurements was carried out to determine wavelength conversion factors.
Results are presented for pure aerosol types and frequently observed aerosol
mixtures.
P3.3 Long-term aerosol study on continental scale through ACTRIS/EARLINET vertical
profiles
Lucia Mona, and EARLINET team
EARLINET (European Aerosol Research Lidar Network) has been providing aerosol
optical properties vertical profiles over Europe since May 2000. All EARLINET
stations perform almost simultaneously measurements three times per week
following a scheduling established in 2000. Besides these climatological
measurements, additional measurements are performed in order to monitor
special events (as volcanic eruptions and desert dust intrusion), for satellite data
evaluation and integrated studies and during intensive measurements
campaigns. Aerosol optical properties vertical profiles are freely available at
www.earlinet.org and through ACRIS data center http://www.actris.net/. This
data are currently published on the CERA database with an associated doi
number.
Long-term aerosol observations performed within EARLINET allows a
climatological study of aerosol properties over Europe. In particular, EARLINET
Raman stations provide direct measurement of extinction profiles, and therefore
of the aerosol optical depth (AOD), a key parameter for understanding the
aerosol role on radiation budget. The free troposphere contribution to AOD and
altitude of lofted layers are provided thanks to the vertical profiling capability of
lidar technique. The representativeness of EARLINET regular scheduling for
climatological studies is investigating through the comparison with AERONET and
MODIS measurements. We find that the regular measurements schedule is
sufficient for climatological studies. In addition lidar punctual measurements are
representative for a larger area (1°x1°) in a climatological sense. Long term
analysis of EARLINET profiles shows that the AOD in generally decreasing over
Europe in agreement with both passive-sensors and in situ measurements.
Moreover, a reduction of the contribution to the total AOD of the lowest altitude
range is found in particular for the Central Mediterranean region. The analysis of
lidar ratio and Angstrom exponent values Indicates a slight modifications towards
less polluted and bigger particles in the PBL over Europe.
P3.4 Aerosol Extinction Profiles With The Emep Model: First Evaluation Through
Earlinet Profiles
S. Tsyro,M. Schulz, L. Mona, N. Papagiannopoulos, W. Aas
One of the main applications of the EMEP/MSC-W model is to provide - for policy
related assessments - the calculations of current levels and future scenarios of
PM10 and PM2.5. Accurate calculation of mineral dust is important to reproduce
PM levels and episodes, including exceedances of critical values. Good estimates
of mineral dust deposition are necessary forassessment of ecosystems recovery
from acidification due to base cautions.On the global scale, accurate modeling of
desert dust is essential for making robust estimates of aerosol loads, solar
radiation extinction and aerosol radiative effects.
EARLINET aerosol extinction profiles measured during the ACTRIS Summer 2012
Campaign are compared to EMEP model for evaluating model performance in
35
terms of dust contribution and of aerosol extinction.
The model runs are performed on both regional and global scales. Modeling of
windblown dust is associated with large uncertainties, therefore a series of tests
is performed to study the sensitivity of results to uncertain parameterization and
input parameters.Furthermore, as windblown dust generation is rather a sub-grid
process, the effect of model’s resolution on calculated dust concentrations is
considered.
We make combined use of observed and modeled dust data to look closer at dust
events. In addition to situ PM measurements, EARLINET aerosol extinction profiles
have facilitated identifying such events. Understanding air pollution episodes in
Southern Europe requires taking into account Saharan dust intrusions. Making
use of EMEP global calculations, we show the advantage of using in the regional
scale EMEP model time resolved, consistent boundary conditions as opposed to
climatological dust fields.
P4.1 Real-time detection of Bioaerosols by Mass Spectrometry and Fluorescence
methods during the BIODETECT 2014 campaign at CEA/LSCE/ACTRIS SUPERSITE
(Saclay, France)
R. Sarda-Estève, J. Sciare, N.Bonnaire, C. Junot, F. Fennaille, F. Bercher, M.
Thibaudon, B.Baisnee, M. Gallagher, A. Gabey, V. E. Foot, J. A. Huffman, U.
Pöschl, H.Su, D. Kiselev, S.Sampo, O. Favez, J. Jayne,P. Croteau, A. Prevot, A.
Vlachou, I.El. Haddad, J-M. Roux, M. H. Nadal, C. Bossuet and L. Olmedo
The French Atomic Energy Commission (CEA) has developed a new on line mass
spectrometry method to detect atmospheric fungal spores (Sarda Esteve et al.,
AAAR 2013) under the Bio Chemical Collectors (BCC) research project. This
method has been compared with a traditional method from the National Network
of Survey for Airborne contaminants (RNSA) to identify Cladosporium events and
has shown good agreement with microscopy techniques. Real-time
measurements of bio-aerosols using light-induced fluorescence (LIF) techniques
have also been performed widely, both for bio-aerosol quantification and to
support ice nucleation studies (e.g. Despres et al., 2012). Recent work has sought
to better understand the variability in observed fluorescence recorded using LIF
instruments (Huffman et al., 2013, O’Connor et al., 2014). Novel data analysis
methods are also required to effectively interpret the datasets produced by such
instruments, which can exhibit high dimensionality. Robinson et al., (2013)
successfully distinguished between calibration particles measured using a WIBS
4A by applying a clustering algorithm to the data. They went on to apply this
algorithm to ambient datasets and attributed particular clusters to bacteria and
fungal spores (Crawford et al., 2014).
To understand the major processes affecting fluorescent aerosol particles, it is
necessary to intercompare these real-time methods with measurements of
biological targets that provide more detailed chemical information, such as real-
time mass spectrometry. An intensive measurement campaign, BIODETECT 2014,
will take place at the LSCE-SIRTA ACTRIS supersite outside Paris in summer
between the 7th of July and the 8th of August. This study may help identify
potential new technologies for monitoring the spread of airborne pathogens and
other bio-aerosols. During this period of the year, bacteria and fungal spore are
expected to be emitted to the air in high concentration. These bio-aerosol events
36
can be used as proxies for airborne pathogens spreading through an
urban/suburban influenced environment.
P4.2 Direct, longwave radiative forcing of mineral dust: sensitivity study and
improvement of its estimation by means of tools recently developed by the
EARLINET community
Michaël Sicard, Constantino Muñoz, Adolfo Comerón, Alejandro Rodríguez
Atmospheric aerosols have a remarkable effect on the Earth‐atmosphere
radiative budget. Indeed, aerosols and their interactions with clouds contribute to
the largest uncertainties in the estimation of the Earth’s changing energy budget.
Nowadays many radiative transfer models have been developed to locally
estimate the aerosol direct radiative forcing (RF). In the longwave (LW) spectral
range, the aerosol radiative properties are usually estimated theoretically with a
Mie code. The parameter that contains the absorption and scattering quantities,
the extinction coefficient, is normalized to the extinction coefficient in the
shortwave spectral range, most of the time in the visible spectral range, or to the
number concentration. As measurements of the extinction coefficient or of its
integral, the optical thickness, are available in the shortwave spectral range, the
equivalent extinction coefficient or optical thickness in the LW spectral range
can be deduced thanks to that normalized, theoretical extinction coefficient.
The first objective of this research is to perform a sensitivity study of mineral dust
direct radiative forcing as a function of their properties. The radiative transfer
model GAME, which can compute vertically resolved shortwave and longwave
values of aerosol radiative forcing, is used. Before developing the sensitivity
analysis, the aerosol radiative transfer model is validated by comparing
its outputs with results published previously. Radiative forcing simulations in the
longwave show an important sensitivity to the following parameters: aerosol size
and refractive index, aerosol vertical distribution, humidity, surface temperature
and albedo. The second objective of this work is to investigate how the knowledge
of the vertically‐resolved fine and coarse mode aerosol optical thickness modifies
the LW RF. Since relatively little the EARLINET community has developed codes
that combine sun‐photometer and lidar data to retrieve a set of parameters
vertically‐resolved related to the size distribution (fine and coarse mode extinction
coefficients, fine and coarse mode volumetric concentrations, etc.). We
concentrate on the case of mineral dust whose size distribution is often
dominated by the coarse mode. This work demonstrates that the knowledge of
the vertically‐resolved fine and coarse mode aerosol optical thickness modifies
the LW RF as compared to the classical approach with a total aerosol optical
thickness. The results show that when the coarse mode predominates the
classical approach underestimates the dust LW RF by 4 to 20 %.
P4.3 OC and EC analyzed in PM using thermo-graphic or thermo-optical method at
Melpitz site in Germany– a comparison for 2012-13
Gerald Spindler, Anke Rödger, Laurent Poulain, Konrad Müller, Hartmut
Herrmann
Since 2002 organic carbon (OC) and elemental carbon (EC), in sum total carbon
(TC), were quantified at TROPOS with a carbon analyzer, (C/Smax) using the VDI-
Method (TGVDI), for quartz filter high-volume-samples (HV).
In 2012 the thermo-optical method (TO) be introduced (Sunset Laboratory Inc.) to
provide comparable results for the daily PM10, PM2.5 and PM1 samples from
37
Melpitz site for international networks (ACTRIS, EMEP). The most common
temperature protocol in Europe EUSAAR2 with transmission detection was used
(TOTEUSAAR2).
To avoid parallel analysis we derive empirical factors (F) to recalculate OC, EC and
TC from 21 month (start January 2012) from TG and TO analysis (equation 1)
[OC;EC;TC]TGVDI = F x [OC;EC;TC]TOTEUSAAR2 (1)
TGVDI deliver TC results which are in the mean about 85% lower than for
TOTEUSAAR2. The reason is the lower temperature (650°C) in comparison to the
final temperature of the EUSAAR2-protocoll (850°C). The TGVDI without charring
correction provides in the mean lower OC values (F=0.72) and higher EC values
(F=1.58) in comparison to TOTEUSAAR2. All derived F show very low variability’s
for the particle sizes (PM10, PM2.5, PM1). Factors F are 0.68 (0.76) for OC, 1.42
(1.68) for EC, and 0.85 (0.85) for TC, respectively, for days with air-mass type
marine compared to continental (in brackets). A comparison between summer
and winter (in brackets) results in F of 0.64 (0.76) for OC, 2.23 (1.44) for EC and
0.83 (0.86) for TC. In summary, for the whole time the factor F show a minor
variability and allows re-calculation of long-time means for OC, EC and TC.
For means over season or over days with different air masses a re-calculation only
for TC can recommended, the split between OC and EC may vary.
A comparison for PM1 OC between TOTEUSAAR2 and AMS-measurements gives
indication for a more realistic chemically originated result.
P4.4 BASTA – FMCW Cloud radar at SIRTA
Julien Delanoë, Jean‐Paul Vinson, Williams Brett, Christophe Caudoux, Fabrice
Bertrand, Ruben Hallali, Jacques Parent du Chatelet, Alain Protat, Martial
Haeffelin, Jean‐Charles Dupont
France LATMOS (CNRS/UVSQ/UPMC) laboratory has extensive experience in the
meteorological field and especially in cloud observation using Doppler radar. We
have recently developed a new cloud Doppler radar at 95GHz, called BASTA. The
BASTA Doppler radar is a frequency modulated continuous wave (FMCW) radar
and it does not require high transmitting power unlike very expensive pulsed
radar. This technical option takes advantage of the latest developments in signal
processing techniques and allows one to drastically reduce the price of the
emitter. Our in house prototype provides real time 24/7 vertical observations and
has been operated for several years without any significant failure at SIRTA
(Palaiseau, France). This radar is ideal for cloud and fog studies. Four
simultaneous resolutions are available: for instance a 12.5m resolution is
dedicated to low clouds and fog, a 25m resolution is dedicated to midlevel clouds
and, 100m and 200m resolutions are especially designed for high altitude ice
clouds such as cirrus up to 12 km. Therefore this radar opens a way to cloud radar
networking due to its relative low coast and its simplicity to operate. It is also
envisioned to deploy such a radar on airports to monitor fog and contribute to
improve security. Due to its technical characteristics this radar can be easily
calibrated using a target mounted on a mast. This advantage coupled to its high
mobile capability could make it a mobile calibrator for radars that are more
challenging to calibrate. We will present our latest version of the prototype and a
few results. Session 1: Scientific achievements at ACTRIS stations.
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P4.5 Analysis of Highly Time- and Size-Resolved Particle Number Size Distribution
Data at Košetice station
Naděžda Zíková, Jakub Ondráček, Jaroslav Schwarz, Jiří Smolík, Vladimír Ždímal
Five years of continuous SMPS data measured at the rural background station
Košetice observatory is presented, and the first two years of data are statistically
analyzed. The evaluation was performed on time scales from years to days, and
an overall new particle formation (NPF) frequency analysis was done as well. The
annual average total concentration was found to be 6.6 x 103 #/ccm, the particle
size distribution has a well expressed accumulation mode and high variability in
particles sizes below 50 nm. In the seasonal data, particles of the smallest sizes
(smaller than 50 nm) were of high concentrations in summer, on the contrary, of
the lowest concentrations in winter. Particles of the biggest sizes (over 300 nm)
showed the opposite behaviour. The analysis of NPF events revealed a strong
annual cycle peaking in spring and summer and dropping in winter. In monthly
data, the global minimal of total concentrations was recorded in December, the
global maximum in June. Weekly cycle analysis proved that the station is suitably
characterised as a rural background – the weekly cycle was statistically
insignificant on most days. The typical daily cycle of total concentrations showed
its minimum between 3 and 6 AM, its maximum at about 6 PM. Particles under
50 nm in diameter, compared to particles larger than 50 nm, exhibited higher
daily amplitude.
P4.6 Combining vertical-wind statistics and Cloudnet microphysical products in mid-
level clouds
Johannes Bühl, Patric Seifert, Ronny Engelmann, and Albert Ansmann
Mixed-phase altocumulus or altostratus clouds should glaciate within minutes,
due to the Wegener-Bergeron-Findeisen process. Observations of mixed-phase
mid-level clouds (2-8 km height) contradict this expectation. They were found to
be stable over hours in ground-based experiments at our field sites and in aircraft
measurements. The main reason for that are permanently occurring up- and
downdrafts. To observe such complex scenarios from the ground, combined lidar
and radar measurements are essential.
We probe mid-level mixed-phase clouds (altocumulus, altostratus) with a
vertically pointing Doppler lidar, a depolarization lidar, a microwave radiometer
and a 35-GHz cloud radar to investigate the impact of atmospheric upward and
downward motion on the physical phase composition of these clouds. The vertical
velocities at cloud base (Doppler lidar) and the microphysical properties of the
clouds (Cloudnet retrievals from combined radar, microwave and lidar
observations) are obtained simultaneously. We identify virga particles below the
clouds and discriminate ice particles and droplets by means of the depolarization
lidar and radar techniques.
Comprehensive statistics of cloud phases and their associated vertical velocities
are established from Cloudnet microphysical products combined with Doppler
lidar measurements. Case studies from the SAMUM-2 campaign at Cape Verde
(2008) and from the UDINE campaign (Up- and Downdrafts and Drop and Ice
Nucleation Experiment) at Leipzig (2010-2013) are presented to compare cloud
properties in tropical and mid-latitude environments.
39
P4.7 Investigation of aerosol-cloud interactions with dual-field-of-view Raman lidar
measurements
Jörg Schmidt, Johannes Bühl, Albert Ansmann, and Ulla Wandinger
This study investigates aerosol-cloud interactions over Leipzig, Germany, by
means of the dual-field-of-view (dual-FOV) Raman lidar technique. Thereby, it
serves the ACTRIS WP22 “A framework for cloud-aerosol interaction studies”.
Dual-FOV Raman lidar probings of water clouds are performed with two FOVs. In
this way, profiles of the cloud extinction coefficient, cloud droplet effective radius,
liquid water content (LWC), and cloud droplet number concentration (CDNC) are
obtained up to a penetration depth of about 150 m.
Twenty-nine dual-FOV Raman lidar measurements are considered for a statistical
analysis of aerosol-cloud interactions. The correlation between the aerosol
particle extinction coefficient a below the cloud and the CDNC N at cloud base is
investigated by means of ACIN values (ACIN =
- d ln N / d ln a). For the aerosol layer which stretches from 300 to 1000 m below
cloud base height and the CDNC obtained 30 to 70 m above cloud base ACIN =
0.32 +/- 0.19 is obtained.
Through the cloud-profiling capability of the dual-FOV Raman lidar technique, the
dependence of ACIN on the cloud penetration depth is investigated. A strong
decrease of aerosol-cloud correlation to ACIN = 0.00 +/- 0.31 is observed for a
higher cloud penetration depth of 70 to 120 m. This finding corroborates that
aerosol-cloud interactions are most pronounced at cloud base where the aerosol
particles are mixed into the cloud and other cloud processes are less dominant.
Furthermore, the effect of the vertical wind speed on aerosol-cloud interactions is
investigated with combined measurements of the dual-FOV Raman lidar and a
Doppler wind lidar. Significantly higher ACIN values are obtained for cloud
updraft regions with ACIN = 0.77 +/- 0.36 and ACIN = 0.41 +/- 0.39 for cloud
penetration depths of 30 to 70 m and 70 to 120 m, respectively.
This study investigates aerosol-cloud interactions over Leipzig, Germany, by
means of the dual-field-of-view (dual-FOV) Raman lidar technique. Thereby, it
serves the ACTRIS WP22 “A framework for cloud-aerosol interaction studies”.
Dual-FOV Raman lidar probings of water clouds are performed with two FOVs. In
this way, profiles of the cloud extinction coefficient, cloud droplet effective radius,
liquid water content (LWC), and cloud droplet number concentration (CDNC) are
obtained up to a penetration depth of about 150 m.
Twenty-nine dual-FOV Raman lidar measurements are considered for a statistical
analysis of aerosol-cloud interactions. The correlation between the aerosol
particle extinction coefficient a below the cloud and the CDNC N at cloud base is
investigated by means of ACIN values (ACIN =
- d ln N / d ln a). For the aerosol layer which stretches from 300 to 1000 m below
cloud base height and the CDNC obtained 30 to 70 m above cloud base ACIN =
0.32 +/- 0.19 is obtained.
Through the cloud-profiling capability of the dual-FOV Raman lidar technique, the
40
dependence of ACIN on the cloud penetration depth is investigated. A strong
decrease of aerosol-cloud correlation to ACIN = 0.00 +/- 0.31 is observed for a
higher cloud penetration depth of 70 to 120 m. This finding corroborates that
aerosol-cloud interactions are most pronounced at cloud base where the aerosol
particles are mixed into the cloud and other cloud processes are less dominant.
Furthermore, the effect of the vertical wind speed on aerosol-cloud interactions is
investigated with combined measurements of the dual-FOV Raman lidar and a
Doppler wind lidar. Significantly higher ACIN values are obtained for cloud
updraft regions with ACIN = 0.77 +/- 0.36 and ACIN = 0.41 +/- 0.39 for cloud
penetration depths of 30 to 70 m and 70 to 120 m, respectively.
P4.8 The relationship between aerosol properties, temperature, and the efficiency
of heterogeneous ice formation as observed with lidar
Patric Seifert, Thomas Kanitz, and Albert Ansmann
The vertical distribution of ice and super-cooled liquid water fundamentally
controls the radiation budget of the atmosphere and the type and intensity of
precipitation. Long-term lidar observations performed within EARLINET by
TROPOS, Leipzig, Germany were used to investigate the relationship between
temperature and the probability of heterogeneous ice formation in super-cooled
clouds for atmospheric temperatures between 0 and -40 °C. These studies dealt
with three main questions: How does (1) Saharan dust and (2) volcanic ash affect
the efficiency of heterogeneous ice nucleation as a function of cloud-top
temperature and (3) how efficient does heterogeneous ice formation occur in the
rather aerosol-burden atmosphere above Central Europe compared to other
regions of the Earth?
Information about the temporal and vertical extent of the observed cloud layers
were obtained from the received range-corrected signal. The phase state (either
pure liquid or ice-containing) was derived from the volume linear depolarization
ratio measured with lidar.
The analysis of ten years of lidar measurements at TROPOS revealed that clouds
contain ice 50% more frequently at cloud-top temperatures between -15 and -10
°C under dust-laden conditions compared to dust-free conditions (75% instead of
50%). Similar results as for dust-laden conditions were obtained for clouds
embedded in volcanic ash after the eruption of the Eyjafjallajökull volcano in April
2010. From the comparison of the long-term Leipzig dataset to respective
datasets from Punta Arenas, Chile and Praia, Cape Verde it was found that
heterogeneous ice formation is in general more efficient over Central Europe. At
the tropical and southern-hemispheric sites of Praia and Punta Arenas,
respectively, significant ice formation was only observed at temperatures below -
20 °C. This finding implies that the rather high background aerosol load in the
northern midlatitudes has a strong impact on the efficiency of heterogeneous ice
formation.
P4.9 Joint analysis of continental and regional background environments in the
Western Mediterranean: PM1 and PM10 concentrations and composition
A. Ripoll, M. C. Minguillón, J. Pey, N. Pérez, X. Querol, A. Alastuey
Atmospheric aerosol concentrations and composition were simultaneously
41
studied at a continental (Montsec, MSC, 1570 m a.s.l.) and a regional (Montseny,
MSY, 720 m a.s.l) background site in the Western Mediterranean Basin (WMB) for
a 3 year period.
Time variation of aerosol concentrations and composition was investigated as a
function of the origin of air masses. The diverse meteorological episodes showed
different influence at regional and continental scale. When long-range transport
from Central and Eastern Europe and from North Africa occurs, the continental
background site is frequently more influenced, thus indicating a preferential
transport at high altitude layers. Conversely, the regional background was more
influenced by regional processes. In winter, anticyclonic conditions enhance the
stagnation of air masses with the consequent accumulation of pollutants at
regional scale in the WMB, whereas the continental background site remains in
the free troposphere. Totally different conditions drive the aerosol
phenomenology in summer. Weak pressure gradients and elevated insolation
generate recirculation of air masses and enhances the development of the PBL,
causing the aging of aerosols and incrementing pollutant concentrations over a
larger area, including the continental background. This is reflected in a more
similar relative composition and absolute concentrations of PM components at
both regional and continental background environments in the warmer season
Our results highlight the importance of the NPF processes in southern Europe,
reveal a relatively lower contribution of anthropogenic pollutants (mainly
biomass combustion) with respect to central Europe, and underline the
contribution of natural long-range transport such as Saharan dust.
P4.10 Results of the ACTRIS NA 4 VOC Round Robin Intercomparison Experiment for
Monoterpenes
Anja Werner, C. C. Hoerger, C. Plass-Duelmer, S. Reimann, R. Steinbrecher, E.
Eckart, N. Bonnaire, A. Colomb, R. Connolly, J. Diskova, P. Dummitrean, C. Ehlers,
V. Gros, H. Hakola, M. Hill, J. R.Hopkins, J. Jaeger, M. Leuchner, K. Michl, E.
Nemitz, S. Sauvage
Biogenic volatile organic compounds (BVOC) play an important role in summer-
time tropospheric chemistry and in secondary organic aerosol formation. They are
produced by vegetation under daylight conditions and are mainly depleted by
reaction with OH and O3, yielding atmospheric lifetimes of minutes to hours. The
amount in the atmosphere thus varies between less than 1ppt to few ppb and the
rather reactive compounds are challenging to quantify. State of the art
instrumentation for BVOC is usually gas chromatography with either flame
ionization detection (GC-FID) or with mass spectrometry (GC-MS). The Proton
Transfer mass spectrometry (PTR-MS) is able to measure monoterpenes in an air
stream directly, but cannot specify between individual BVOCs. However, GC-
systems have the ability to quantitate individual compounds, but they require a
complex multi-step sample preparation process which represents a large
potential for errors. Further challenge is a proper calibration, which is usually
performed with pressurized whole air or synthetic mixtures stored in cylinders or
by liquid injection.
In order to evaluate the performance of the available instruments within ACTRIS
VOC network, a Round-Robin-intercomparison for VOC was performed in NA4
(Trace gases networking: Volatile organic carbon and nitrogen oxides). Two sets
of test gases comprising each a cylinder with a whole air sample and a cylinder
with a synthetic 30-component VOC in N2 mixture were circled among twenty
42
stations all over Europe. Results of this intercomparison for alkanes, alkenes,
alkynes and aromatics are shown in an accompanying presentation by C. C.
Hoerger et al.. The synthetic VOC mixture included nine monoterpenes and also
three trimethylbenzenes. These were measured by a subset of the participating
stations applying different GC-FID and GC-MS techniques and results will be
shown here.
P4.11 Study of droplet activation in thin clouds using ground-based lidar, Doppler
radar and microwave techniques
M. Rosoldi, P. Gumà Claramunt, F. Madonna, F. Amato, A. Amodeo, G. D’Amico,
A. Giunta, L. Mona, N. Papagiannopoulos and G. Pappalardo
Clouds change their macrophysical, microphysical and optical properties as a
result of their interaction with aerosols. These processes are still not accurately
quantified and parameterized in weather and climate numerical models and
accurate estimations of aerosol and cloud properties, using surface-based
measurements , are needed to improve their modeling.
Thin liquid water clouds represent an interesting target to infer quantitative
information on droplet activation process, because ground-based active remote
sensing techniques, such as Raman lidars and cloud Doppler radars, allow us to
obtain vertical profiles of aerosol, water vapor and cloud properties below, inside
and above these clouds with high vertical and temporal resolution.
In this work, observations of thin liquid clouds performed in the period 2010-2013
using multi-wavelength Raman lidars, a cloud Ka-band Doppler radar and a
microwave radiometer operating at CNR-IMAA Atmospheric Observatory (CIAO –
40.60N, 15.72E, 760 m a.s.l.), located in Potenza, Southern Italy, are considered.
Particular attention is devoted to the observation of “broken clouds”, defined as
groups of clouds separated by free cloud regions. These clouds are particularly
interesting because they allow us to study the variability of aerosol optical
properties and relative humidity (RH) in the transition from the cloudy to the
cloudless region.
In this work, a methodology to characterize this variability and to gain a better
insight into droplet activation process is proposed. Through this methodology
several cloud properties, such as the vertical extension of the activation region,
the height and temperature of cloud base and cloud top, the cloud layer thickness
and liquid water path (LWP), are estimated.
Statistics over a selected dataset will be presented, including the correlation
between thermodynamic properties of atmosphere, aerosol type and
updrafts/downdrafts retrieved using a Doppler radar.
P4.12 Continuose Observations of Anthropogenic VOCs at Monte Cimone (Italy):
Trends and Emissions
Jgor Arduini, Eleonora Lo Vullo, Francesco Furlani, Umberto Giostra, Francesco
Graziosi and Michela Maione
Anthropogenic volatile organic compound (VOCs) play a very important role as
primary hazardous air pollutants as well as in the photochemical formation of
tropospheric ozone, peroxycarboxylic nitric anhydrides, formaldehyde and
secondary organic aerosols. Monitoring and modelling of the spatiotemporal
distribution of these species is important for better understanding atmospheric
processes affecting both climate and air quality.
43
For this reason, speciated VOCs and carbon monoxide (CO) continuose
measurements are carried out at the WMO-GAW global station at Monte
Cimone, a background site in proximity of the highly polluted Po Basin in Northern
Italy. In this study we have analysed four-year (2010-2013) time series of C2-C6
alkanes, benzene, toluene, ethyl-benzene, xylenes and CO in order to derive
trends and seasonal cycles, to identify emission sources and to study the impact
of such emissions on the oxidation chemistry.
As observed in other European sites, the VOCs atmospheric mixing ratios
measured at Monte Cimone showed a decline over the study period. We used the
correlation between CO and VOCs in order to characterise emission sources. In
addition, we used the seasonality in the ratios of isomeric alkane pairs (butanes
and pentanes) in order to assess the effects of atmospheric transport. Finally,
concentration ratios of VOCs with different rates of removal have been used as
indicators of photochemical processing.
P4.13 Comparison of spheres and spheroids particles on the closure studies for
microphysical-optical properties
M. Sorribas, F. J. Olmo, A. Quirantes, M. Gil-Ojeda and L. Alados-Arboledas
The natural and anthropogenic atmospheric particles alter the Earth’s energy
budget and they are drivers of climate change. To evaluate the influence of
aerosols on the solar radiation a rigorous knowledge of the absorption and
scattering processes is needed. The aerosols rarely exhibit a spherical shape,
being its geometry more complex. In order to carry out studies about the
scattering properties, theoretical calculations are computed using the Mie or the
T-matrix Theories, assuming homogeneous and spherical particles or non-
spherical particles, respectively.
The Mie model and T-matrix code can be also used to clarify the uncertainties
associated with the instrumentation for measuring microphysical and optical
aerosol properties. One example of this application is the study of the uncertainty
of an integrated nephelometer, instrument widely used to measure the aerosol
scattering and backscattering properties. It integrates the scattered light by the
particles from a volume of air ideally over a full range of angles from 0º to 180º.
A systematic uncertainty of the integrating nephelometry technique is that the
light scattered is truncated near-forward and near-backward direction below 7º
and 10º, respectively. This limitation is commonly known as the angular
truncation error. One of the most popular corrections was presented in Anderson
and Ogren (1998), where a parameterization of the truncation correction is
determined by the ratio between full and truncated scattering computed by Mie
Theory. However, this correction has some limitations related to the particle
shape and size range.
In this study we present the results of a field campaign performed to examine
instrumental closure in aerosol optical and microphysical properties with the aim:
(1) to compare the observed and the computed optical properties, using the
spherical and spheroids approximations; and (2) to analyse the angular
truncation correction in terms of sub- and super-micron particles size ranges.
P4.14 Atmospheric boundary layer and ozone-aerosols dynamics under dusty
conditions from saharan intrusions
J.A. Adame, C. Córdoba-Jabonero, M. Sorribas, D. Toledo and M. Gil-Ojeda
44
In the framework of AMISOC (Atmospheric Minor Species relevant to the Ozone
Chemistry) project a campaign was carried out at El Arenosillo observatory
(INTA/ARN station, 37.1º N 6.7º W, 40 m a.s.l., a coastal area in southwestern
Spain), in May-June 2012. The campaign was focused on the impact of Saharan
dust intrusions in both the Atmospheric Boundary Layer (ABL) and ozone-aerosols
dynamics. In-situ and remote sensing techniques for gases and aerosols
measurements as well as modelling analysis were used. Meteorology features on
surface, ABL structure and evolution, aerosol profiling distribution and aerosol-
ozone interaction on surface were analyzed. In particular, two four-day
measurements periods were selected according to non-dusty (clean conditions)
and dusty (presence of Saharan dust) situations for comparison purposes. In both
aerosol scenarios, sea-land breezes were developed in lower atmosphere whereas
differences were found at upper levels. Results show surface temperatures higher
in 3ºC and lower humidity values during dusty respect to non-dusty period;
thermal structure on surface layer (as estimated by instrumentation located in a
100-m tower) shows differences mainly for nocturnal period and less intense
inversions under dusty conditions. The mixing layer during dusty days presented a
thickness of 400-800 m higher than that observed for non-dusty situation. Dust
presence also disturbed the typical daily ABL evolution and vertical stable
conditions were only observed in early evening during intrusions. During the dusty
days aerosol extinction was 2-3 times higher with the dust layer confined
between 1500 and 5500 m height. Back trajectory analysis confirmed its African
origin. On surface, particle concentration was around 3.5 times higher during
dusty events but local ozone did not exhibit any change. In summary, the arrival
of Saharan dust at upper levels presented a clear impact in meteorological
conditions on surface, inhibited the typical daily evolution of the ABL and caused
an increase in aerosol loading both on surface and at upper altitudes; however,
no dust influence was observed in surface ozone levels.
P4.15 Vertical exchange between the boundary layer and the free troposphere:
Effects on aerosol direct and indirect effects.
Freney, E.J, K.Sellegri, E.Asmi, A. Colomb, M.Hervo, C.Rose, D.Picard.
During February 2012, an exceptional cold event was experienced across Europe.
This cold event was due to a large area of high pressure over Eastern Europe.
Using in-situ measurements of aerosol chemical and physical properties at the
puy de Dome station, as well as LIDAR measurements on aerosol vertical profiles
we studied the exchange between the boundary layer and the free troposphere
during this cold event. Temperatures ranged from -10oC to -18oC, and LIDAR
measurements showed that the puy de Dome station was alternatively sampling
clean regional airmasses in the free troposphere (FT), and sampling
anthropogenic emissions from the surrounding area within the boundary layer
(BL). Within the FT, we observed a gradual change in aerosol physical properties
with increases in aerosol mass concentrations of up to 4 times the starting
concentration (Figure 1), as well as increases in the number of larger particles
(>150 nm). Aerosol chemical properties did not show any significant changes but
increases in organic and nitrate particles were observed. This work discusses
these observations as well as their effects on aerosol direct (aerosol optical
properties) and indirect properties (cloud condensation nuclei).
P4.16 Measurements of volatile organic compounds (VOCs) and NOx within ACTRIS at
45
the puy de Dôme research station (France, 1465m a.s.l.) since spring 2011
A.Colomb, V. Jacob, L. Bouvier, J-M. Pichon, H. Perroux, M. Ribeiro, E. Freney, C.
Rose, C. Gaimoz, J. Fleuret, E.Dumas and K. Sellegri
The high altitude puy de Dôme research station is located in central France (45°
46’ N, 2° 57’ E, 1465 m a.s.l.), 16km away from the city of Clermont-Ferrand. This
station has been classified as representative background. At the summit,
meteorological parameters including wind speed and direction, temperature,
pressure, relative humidity and radiation, atmospheric trace gases (O3, NOx, SO2,
CO2, CO), and aerosol physical, optical and chemical properties (particle size,
black carbon, mass,..) are measured since years.
In spring 2011, cartridges sampling program was started to link the observations
of VOC within ACTRIS at the puy de Dôme research station. Selected volatile
organic compounds (VOCs, including a large set of non-methane hydrocarbons
and some terpenes (isoprene, α-pinene and some oxygenated and halogenated
compounds) were measured during a precampaign in summer 2010, and
intensive field campaigns in spring 2011, summer and winter 2011, 2012, 2013.
The analysis of VOCs collected on Tenax/Carbosieve III cartridges was achieved by
using thermo-desorption coupled gas-chromatography with mass spectrometry
(GC-MS). In order to determine the transport pathways of the air masses prior to
arriving at the pdD site, the Hybrid Single Particle Lagrangian Trajectory (HYSPLIT)
model was used. Trajectories were classified according to their predominant
transport direction prior to measurement as either continental (C), marine (M),
marine modified (Mod), Mediterranean (Med), or mixed depending on their
pathways.
The results presented here are discussed in terms of observed levels, diurnal
variability and sources influence of these gaseous pollutants.
Comparisons with other tracers (NOx (with ACTRIS recommendations)., CO, BC,
…), with aerosols (chemical or physical properties) and other parameters
(temperature, air masses origins, planetary boundary layer height,…), are used to
help identifying main parameters influencing VOCs variability. Role of VOCs as
precursors of oxidants and secondary organic aerosols will be discussed.
P4.17 Linking field and laboratory studies on particle formation
H.E. Manninen, K. Lehtipalo, P.P. Aalto, J. Backman, S. Buenrosto Mazon, X. Chen,
J. Duplissy, A. Franchin, J. Hong, N. Kalivitis, J. Kangasluoma, J. Kontkanen, F.
Korhonen, R. Krecji, J. Lampilahti, K. Leino, G. Steiner, R. Väänänen, R. Wagner, D.
Wimmer, T. Petäjä, And M. Kulmala
New particle formation (NPF), starting from molecular cluster sizes, happens
frequently in the atmosphere. These charged and neutral clusters are climatically
important if they grow to sizes when they can act as seed for cloud droplets. The
occurrence of NPF has been observed in all kind of environments where we have
been measuring from continental to marine and from Antarctic to tropical
environments. The ion spectrometers (Neutral Cluster and Air Ion Spectrometer,
NAIS) and the Particle Size Magnifier (PSM) allow starting the aerosol
measurements from the sizes of molecular clusters and nucleating particles (~1-2
nm in mobility diameter). The PSM and NAIS can also be used to resolve directly
46
the particle nucleation rate and growth rate, which are the dominant factors in
determining how much and what kind cloud droplets can be produced via NPF.
Using these instruments together with mass spectrometric methods, one can
solve both the concentration and composition of the nucleating clusters and their
precursor vapours. This approach have been used e.g. on field at the Hyytiälä
SMEAR II station in Southern Finland and during CLOUD laboratory experiments
at CERN. The laboratory and chamber studies are essential to deepen the
mechanistic understanding of the NPF. Our speciality is the comprehensive, long-
term field measurements conducted at the boreal forest SMEARII site. We have
measured both inside the boreal forest and also at different altitudes above the
forest at a tower and on-board an instrumented aircraft, a hot-air balloon and
recently a zeppelin. By comparing atmospheric cluster and particle measurements
from different instruments and different sites we have shown that most of the
sub-3 nm clusters are originally neutral, seen that the appearance of sub-3 nm
clusters is connected to a high probability of NPF events, and learned about the
horizontal and vertical extent of the NPF.
P4.18 Multiple daytime nucleation events at the high altitude station of Chacaltaya
(5240 m a.s.l.), Bolivia
C. Rose, K. Sellegri, F. Velarde, I. Moreno, M. Ramonet, K. Weinhold, M. Andrade,
A. Wiedensohler, and P. Laj
While nucleation may represent one of the major process responsible for the total
aerosol number burden in the atmosphere, and especially at high altitude, the
occurrence of new particle formation (NPF) events are poorly documented in the
literature for high altitude sites. NPF events were detected and analysed at the
highest measurement site in the world, Chacaltaya (5240 m a.s.l.), Bolivia,
between January 1 and December 31 2012, using a Neutral Aerosol and Ion
Spectrometer (NAIS). NPF frequency at Chacaltaya is one of the highest reported
so far (63.9%) and shows a clear seasonal dependency with maximum up to 100%
during the dry season. This high seasonality of the NPF events frequency was
found to be likely linked to the presence of cloud in the vicinity of the station
during the wet season. Multiple NPF events are seen on almost 50% of event
days, increasing the potential of nucleation to be the major contributor to the
particle number concentrations in the upper troposphere. The median particle
formation rate computed for first position events is
increased during the dry season (1.90 cm-3s-1) compared to the wet season (1.02
cm-3s-1), showing that events are more intense, on top of being more frequent
during the dry season. On the contrary, GRs are on average enhanced during the
wet season, which could be explained by higher amount of biogenic volatile
organic compounds transported from the Amazon rainforest. The NPF events
frequency is clearly enhanced when air masses originate from the oceanic sector,
with a frequency of occurrence close to 1. However, based on the growth rate of
the largest particle size range, we calculate that particles most likely nucleate
after the oceanic air masses reach the land and are presumably not originating
from the marine free troposphere. Our observations at CHC suggest that
nucleation and growth are likely to be the major mechanism feeding the upper
atmosphere with aerosol particles.
P4.19 Direct observation of neutral clusters' contribution to new particle formation in
the free troposphere
47
C. Rose, K. Sellegri, E. Asmi, M. Hervo, E. Freney, H. Junninen, J. Duplissy, M.
Sipilä, J.Kontkanen, K. Lehtipalo and M. Kulmala
The formation of new aerosol particles (NPF) in the atmosphere is a key process
influencing the aerosol number concentration as well as the climate, in particular
in the free troposphere (FT) where the newly formed particles directly influence
cloud formation. However, free tropospheric NPF is poorly documented due to
logistic limitations and complex atmospheric dynamics around high altitude
stations that prevent the observation of daytime processes such as NPF in the FT.
Recent improvements in measurement techniques make now possible the
detection of neutral clusters down to ~1-nm sizes, which opens new horizons in
our understanding of the nucleation process. Indeed, only the charged fraction of
clusters have been reported in the upper troposphere up to now. Here we report
observations of charged and neutral clusters (1- to 2.5-nm mobility diameter)
during unusual day-time free tropospheric conditions at the altitude site of Puy de
Dôme (1465m a.s.l.), central France, between 10th and 29th February, 2012. Our
findings demonstrate that in the free troposphere, the formation of 1.5-nm
neutral clusters is about 40 times higher than the one of ionic clusters during NPF
events, indicating that they dominate in the nucleation process. We also observe
that the total cluster concentration increases by a factor of 5.5 during NPF events
compared to the other days, which was not observed for the charged cluster
population in the past. In the FT, the
nucleation process does not seem to be sulphuric acid-limited, as previously
suggested, and could be promoted by the transport of pollutants to the upper
troposphere.
P4.20 ACSM measurements and organic tracers at Montseny during summer EMEP
campaign
María Cruz Minguillón, Anna Ripoll, Barend van Drooge, Xavier Querol and
Andrés Alastuey
The forested regional background ACTRIS site of Montseny (MSY, 41°46'46"N
02°21'29"E, 720 m a.s.l.) was chosen for the present study. It is located in
Northeast Spain, 50 km away from Barcelona, in the Western Mediterranean
Basin. The atmospheric dynamics is regulated by complex climatic and orographic
effects which control the concentration, composition and transport of PM.
An Aerosol Chemical Speciation Monitor (ACSM, Aerodyne Research Inc.) was
deployed at MSY from June 2012 to July 2013, according to the ACTRIS schedule.
The ACSM measures non-refractory submicron aerosol distinguishing organic
aerosol (OA), nitrate, sulphate, ammonium and chloride (Ng et al., 2011). The
ACSM was set to measure with a time resolution of approximately 30 min.
Positive Matrix Factorization (PMF), and complementarily Multilinear Engine
(ME2), of the organic mass spectral data matrix was carried out, providing
information on different sources or types of the OA, such as hydrocarbon-like OA
(HOA, a surrogate of road traffic emissions), biomass burning OA (BBOA), and
two types of oxygenated OA (OOA, a surrogate for secondary OA) with different
degrees of oxidation.
The results shown will focus on the EMEP summer campaign (June-July 2012).
Among the additional measurements, we highlight the organic compounds
analyzed off-line in 24-h PM1 samples, including tracers such as levoglucosan and
hopanes. These results will be shown together with the resolved organic sources
48
from the ACSM dataset, hence being able to confirm the sources found and the
relative contribution to the bulk organic matter.
P4.21 Analysis of a high level of particulate-pollution event in Paris Megacity by
integrating in-situ and remote sensing aerosol/gas measurement at the SIRTA
ACTRIS Observatory.
J-C. Dupont, M. Haeffelin (IPSL/CNRS); J. Badosa (LMD/CNRS); T. Elias (HYGEOS);
N. Bonnaire, V. Gros, M. Ramonet, J. Sciare, G. Tremoy, F. Vimeux (LSCE); O.
Favez (INERIS); P. Goloub (LOA); T. Bourcy, F.Zanghi (Météo-France)
A high level of particulate-pollution event has been observed in Paris Megacity
between 6 and 15 March 2014. The SIRTA Observatory has documented all
atmospheric variables between surface and the top of free troposphere with in-
situ sensors and active/passive remote sensing instruments.
We will describe the instrumental dataset (more than 150 instruments),
meteorological conditions and variability of some species, such as (i) aerosol
(particle mass, chemistry, size distribution and absorption/scattering), (ii) reactive
gas (type, chemistry), (iii) radon and GES and (iv) isotopic species (CO2, CH4 and
H2O).
A specific attention will be given in this presentation to understand the processes
responsible for the high concentration level of thin particles (smaller than 2.5µm
with a medium radius around 0.2µm) in a thin mixing layer (night 200m and day
600-1200m). All these collocated measurements on the Saclay plateau (ACTRIS
platform) is an ideal place to conduct this work. In fact, the chemical analysis
shows that the major part of these particles were secondary aerosols related to
anthropogenic activities such as traffic, wood burning and agriculture. And, the
geochemical tracers, active and passive remote sensing instruments (lidars, cloud
radar, microwave radiometer and sun-photometer) allow us to characterize the
mechanisms leading to this so high particle pollution: (i) role of boundary layer
dynamics (stable, neutral, convective), (ii) role of geographical origin of PM
components (local, regional, European) and (iii) role of liquid phase (fog and
boundary layer cloud). Finally, the impact on solar and ultra-violet downwelling
fluxes will be quantified.
P4.22 Fine and coarse dust separation with polarization lidar
R.-E. Mamouri, A. Nisantzi, D. Hadjimitsis, and Albert Ansmann
A new lidar profiling method is developed that allows us to separate height
profiles of particle backscatter and extinction coefficients, volume, and mass
concentration of fine-mode dust, coarse-mode dust, and the remaining non-dust
aerosol component (haze, smoke, marine). The method is based on measured
profiles of the particle depolarization ratio with polarization lidar and makes use
of fine-mode (particle radius < 500 nm, 14-17%) and coarse-mode dust
depolarization ratios (radius > 500 nm, 39%), measured in the laboratory by Sakai
et al. (Appl. Opt., 2010). The new method enables us to determine the
contribution of mineral dust to the PM1.0 aerosol burden. Furthermore, such size-
resolving observations are very useful to check the potential of dust transport
models to properly describe the emitted dust size distribution, and therefore the
dust cycle and related radiative effects. Recent publications (Kok, ACP, 2011,
Zhang et al., GRL, 2012) suggest that the dust size distribution is controlled by
processes described by the brittle fragmentation theory. These distributions
strongly differ from size distribution parameterizations used in most global
49
circulation models. This aspect has strong implications on dust cycle and
deposition modelling. The new lidar technique is applied to a period with complex
aerosol layering of fine-mode background dust from Turkey and Arabian desert
dust from Syria. The observation was performed at the combined
EARLINET/AERONET site of Limassol, Cyprus, in September 2011. The dust
profiling methodology and case studies are presented. A consistency study based
on simultaneous observations with EARLINET lidar and AERONET photometer
demonstrate the applicability of the new lidar technique. Good agreement with
AERONET column aerosol observations was found.
P4.23 The Madrid (MAD) station: vertical and ground based measurements of
chemical, physical and optical properties of aerosols
B. Artíñano, F. J. Gómez Moreno, E. Coz, L. Núñez, M. Palacios, A.J. Fernández, E.
Alonso, P. Salvador, M. Becerril, M. Pujadas, A.S.H. Prevot, M. Laborde, S.N.
Pandis
Physicochemical properties of ambient aerosol and atmospheric parameters are
real-time monitored at the CIEMAT research station in Madrid. The site is located
in a sub-urban area northwest the Madrid city. Anthropogenic (typically urban, as
no significant industry is located in the vicinity of the Madrid area) and natural
(mineral dust, biogenic) sources determine the characteristics of the air mass
pollution at this site. Long-range transport processes (European polluted air mass,
African dust outbreaks) have also influence on specific conditions. Urban aerosols
are continuously documented through a number of ground-based measured
parameters: size distribution (SMPS), hygroscopic growth factor (HTDMA),
hygroscopic scattering enhancement (dry-ambient Aurora1000/3000
nephelometers, ACS1000), light absorption and sizeselected BC concentrations
(Aethalometers AE33 and AE31), non-refractory chemical composition (ACSM).
Vertical profiling of tropospheric aerosol and water vapour are obtained at the
site through a LIDAR-Raman instrument integrated in EARLINET (#21 lidar
station). Meteorological parameters and gaseous pollutant concentrations at this
site are provided by a meteorological station (52 m mast) and an active DOAS
system, respectively. In the absence of external inputs, carbonaceous aerosol is
dominant in Madrid. Increasing BC concentrations (about 40% on average of the
PM1), mostly from fossil fuel from traffic and partly from heating systems, seem
to inhibit the hygroscopic growth, partially conditioned by the phase distribution
within the aerosol structure. This enhancement is moderate at high RH, even
during periods of high concentrations of inorganic compounds, which is typical
from polluted areas. A number of aerosol shrinkage processes have been
characterized by the SMPS during nucleation events linked to an increase of wind
speed during the growth phase of the new particles. They mostly occur during
spring and summer periods.
P4.24 Comparison of the aerosol size distribution retrieval from a sun photometer
with in situ measurements at high altitude: taking into account the effect of
water uptake.
Chauvigné Aurélien, Montoux Nadège, Freville Patrick, Hervo Maxime, Sellegri
Karine
Aerosols influence the Earth radiative budget through scattering and absorption
of solar radiation and it is significantly affected by ambient humidity. Several
methods are used to retrieve aerosol properties and thus quantify their direct and
50
indirect impacts on climate. At the Puy de Dôme station, the co-located in situ
measurements at high altitude with parallel remote sensing instruments give
opportunities to evaluate the accuracy of remote sensing retrievals of the aerosol
size distributions. The size distribution retrieve by the Aerosol Robotic Network
(AERONET) Sun photometer observations are compared to the in-situ size
distributions, dry and at ambient relative humididy during a one year period
filtered from cloudy and multi aerosol layers events detected using the LIDAR
backscattering profiles. The hygroscopic growth factors (HGF) were derived by
seasonally segregated parameterization performed over a 4-year period
(Holmgren et al. 2014), and applied to the in situ size distributions. For wet and
dry cases, the sun photometer clearly underestimates diameters for the
accumulation mode and overestimates concentrations for both accumulation and
coarse modes. It appears that the sun photometer underestimation of the aerosol
size is actually higher when the real (wet) size of the aerosol is taken into account.
P4.25 Simulation of improved daytime capabilities of lidar instruments
F. Madonna, A. Amodeo, U.Wandinger
So far, most of the multi-wavelength Raman lidar observations of aerosols are
performed at night, because Raman signals are weak compared to daylight
background. Different techniques have been developed to improve Raman lidar
daytime capabilities in the past years. Indeed, the retrieval of aerosol extinction
during daytime is feasible through the detection of backscattered radiation due to
the pure Rotational Raman Spectrum (PRRS) of molecular nitrogen or oxygen,
much brighter than the vibration-rotation spectrum.
The existing techniques for the measure of PRRS are based on small-bandwidth
emitter and receiver systems and on a small receiver field of view to suppress the
daylight background. They have been successfully tested and implemented in a
few systems which are already in operational use within EARLINET (European
Aerosol research Lidar NETwork).
In this work, several different configurations used as receiver for a lidar system
detecting the PRRS in daytime conditions are compared by means of numerical
simulations. The configurations are mainly differentiated by the design of the
spectral selection unit implemented in the receiver of each lidar system, based on
a narrow-bandwidth filters, grating spectrometers, and hybrid solutions. The
research of configurations able to be more easily implemented on a large number
of lidar systems within ACTRIS are explored.
To improve Raman lidar daytime capabilities, it is also required the use of
receivers able to minimize the region close to the ground level where the lidar
signals are affected by the incomplete overlap between the lidar source and the
receiver FOV, that creates problems to the retrieval of aerosol optical properties.
In addition to this incomplete overlapping problem, the laser signal backscattered
from the close range is not focused on the focal plane of the telescope. In order to
select the best option for the detection of PRRS in the close range (altitudes lower
than about 400-500 m), different telescope options (reflectors and refractors)
have been compared with respect to the potential problems affecting the lidar
measurements in this observation range.
P4.26 Measuring aerosol and water clouds with Raman-Lidar RAMSES
Andrew Reigert, Jens Reichardt
The RAMSES-lidar at the German Meteorological Service’s observatory in
51
Lindenberg was originally designed as a nighttime water vapor measurement
system. It has since outgrown its original purpose and now measures all relevant
lidar parameters, also during the day. It measures water vapor (Raman), nitrogen
(Raman) and elastic backscatter in both near-range receiver and far-range
receiver. In addition the far-range receiver has 2 temperature channels (Raman)
and 2 depolarization channels. At the single emitter wavelength of 355 nm
products such as particle backscatter coefficient, particle extinction coefficient,
lidar ratio and particle depolarization ratio are calculated to characterize clouds
and aerosol.
The water-vapor mixing ratio is calculated from the water vapor channel. The
mixing ratio is then used to calculate the water vapor pressure. Given a
corresponding temperature profile, either from rotational-Raman-, radiosonde- or
microwave radiometer measurements, the water vapor saturation pressure is
calculated. The ratio then provides the relative humidity.
Measurements are done with a high temporal (30 s) and vertical resolution (7.5
m). Depending on measurement quality, signal ratio products (e.g. backscatter
ratio) can be analyzed at full measurement resolution. For other products the
resolution of statistically independent grid points at a height of 4 km can still be
as high as 300 s and 75 m.
All these features make RAMSES uniquely suitable for measuring aerosol
properties very close to the cloud base and thus for studying aerosol-cloud
interactions. Because of the water vapor measurement capability it is possible to
study the effects of increasing relative humidity on aerosol optical properties. The
high measurement resolution makes it possible to measure small scale convective
boundary layer clouds.
Currently, RAMSES has been moved into a new lidar facility, and instrument
improvements are being implemented. It is expected that RAMSES will be fully
operational again in early summer, and that more measurement cases of aerosol-
cloud interactions can be added to the existing data set.
P4.27 8 years of equivalent black carbon observations at GAW/WMO Monte Cimone
station, an analysis of the main contributions affecting its variability
Marinoni A., P. Cristofanelli, D. Putero, T. Landi, L. Bourcier, R. Duchi, M. Busetto,
F. Calzolari, P. Bonasoni
The Mediterranean basin is recognized as a hot-spot region for climate change
and air-quality: it represents a major crossroad for different air mass transport
processes. In particular, large amounts of anthropogenic pollutants emitted in
continental Europe are transported towards the Mediterranean basin especially
during summer, when intense vertical transport is favored by the meteorological
conditions. Moreover, the Mediterranean basin is also affected by large wildfire
events occurring in Europe and in other continents.
Black carbon is one of the most discussed climate forcers, the unique particulate
pollutant acting as “warmer” in the climate system, having also a relatively short
lifetime, thus a faster climate response after emissions reduction. It is emitted
both by anthropogenic sources and natural/anthropogenic biomass burning.
Equivalent black carbon (eqBC) is measured since 2005 at global WMO/GAW
station of Monte Cimone (2165m asl), a sampling site considered representative
of the background conditions of the Southern Europe/Mediterranean Basin.
Atmospheric observations at Monte Cimone are frequently representative of the
free troposphere even if, especially during summer, this measurement site can
52
provide direct information about the injection of anthropogenic pollutants to the
free troposphere of the Mediterranean basin. In this work, we analyzed the
variability of eqBC at Monte Cimone over 8 years of data. To specifically assess
the vertical export of absorbing material from the Po valley to the free
troposphere, we coupled Monte Cimone summer observations with BC
measurements collected in the Po Basin.
Moreover, for evaluating the possible contribution of open vegetation fires to the
variability of eqBC in the Mediterranean area, we coupled satellite observations
(MODIS fire products and land cover type) and deterministic modeling systems
(i.e. Hysplit, WRF). The attempt of separating the different contributions (i.e.
anthropogenic pollution coming from the Po valley and those coming from
natural sources) to the high eqBC concentrations at Monte Cimone was also
carried out.
P4.28 Long-term investigation of Saharan dust transport events at the Mount Cimone
GAW Global Station, Italy (2165 m a.s.l.)
R. Duchia, L. Bourciera, P. Cristofanellia, A. Marinonia, D. Puteroa, T.C. Landia, F.
Calzolaria, M. Busettoa, U.Bonafèa and P. Bonasonia
Due to the high vulnerability to climate change and temperature rise predictions
higher than the global average, Mediterranean basin and Southern Europe are
key areas in understanding long-term regional climate change. They are
frequently interested by the presence of desert dust aerosol transported from
North Africa which plays an important role in climate and environmental system.
Mt. Cimone (2165 m a.s.l., 44°11’N, 10°42’E) is the highest peak of the Italian
northern Apennines and represents the first mountain ridges that Saharan air
masses encounter during their northward displacement towards Europe and
Alpine ranges. Dust transport events (DTEs) have been identified since 2002 at the
CNR baseline global GAW station of Mt. Cimone (CMN) when the atmospheric
concentration of coarse particle (1 μm ≤ Dp≤ 20 μm) significantly increased with
air-masses coming from North Africa as deduced by back-trajectory simulations.
The FLEXTRA three-dimensional back-trajectories analysis also permitted a
statistical climatology of the optical and microphysical properties of the aerosol
according to the origin of the air masses.
Over the investigated period, 15% of time at CMN appeared to be influenced by
dustevents, with maximum of occurrence in spring and summer. Inter-annual
variability of DTEs frequency and magnitude were analysed as a function of
atmospheric transport patterns and climate indexes (e.g. NAO, MEI).
With the aim to investigate the impact of dust transport on aerosol optical
properties over the Mediterranean basin, the absorption and scattering
coefficients during DTEs have been analysed on a seasonal basis. Both scattering
and absorption coefficients clearly showed an increase of the optical capability in
presence of dust, even if on a seasonal basis this increase appeared to be
statistically significant only for spring. While coarse and accumulation particle
number showed significant increases during the identified DTEs, the total aerosol
particle number concentration (10 nm<Dp<3μm) decreased on average.
P4.29 NanoMap: Geographical mapping of atmospheric new particle formation
through analysis of particle number size distribution and trajectory data
Adam Kristensson, Martin Johansson, Erik Swietlicki, Niku Kivekäs, Tareq Hussein,
Tuomo Nieminen, Markku Kulmala, and Miikka Dal Maso
53
New particle formation, potentially responsible for up to 50 % of global cloud
condensation nuclei production, is not monitored all over the world. How often
new particle formation occurs over remote places, and ocean areas is especially
poorly characterized. To remedy this situation, a method has been developed to
map new particle formation up to 500 km away from a field site using only
particle number size distribution and meteorological back trajectory data as
input. Namely, by studying the particle number size distribution at a specific field
site it is possible to observe how newly formed particles in the nanometer size
range are growing by condensation until they reach the size of several tens of
nanometers. The grown particles have been formed as 1.5 nm particles at a
certain distance upwind of the field site, and this place of origin can be traced
with the meteorological back trajectories. An open-access freeware program has
been developed for this analysis. It is called NanoMap, and it has been tested over
the Finnish ACTRIS supersite Hyytiälä. NanoMap shows that new particle
formation at 1.5 nm diameter frequently occurs all over the Finnish continent.
However, it also shows that it occurs over the Baltic Sea, although it is slightly less
frequent than over the Finnish continent for some of the wind directions.
NanoMap can be used at many other sites, and is currently being tested at 2
other ACTRIS supersites, Vavihill and Finokalia in Sweden and Greece,
respectively.
P4.30 Aerosol optical depth changes over Poland, preliminary results and
perspectives
A. Pietruczuk, A. Szkop, M. Posyniak
Atmospheric aerosol is an important factor in climate studies. Besides of that,
measurements of its optical properties are rather sparse in Poland. Long term
observations of aerosol optical properties are conducted at Geophysical
Observatory at Belsk as well as by PoalndAOD network started in 2011. Belsk’s
observatory is placed in a rural region and equipped with sun photometers,
Brewer spectrophotometer and a LIDAR. The LIDAR system is being upgraded to
obtain 3+1 system in far range and 3+2 system in close range.
In this work preliminary results of modification of aerosol optical depth (AOD)
during transport over Poland will be presented. Sunphotomeric data from
AERONET stations located in Belarus, Germany and Sweden as well as satellite
data were used to study changes of AOD between Belsk and chosen stations.
Frequency plots of investigated differences have two modes. One concentrated
around zero and the second one shifted to positive values. This second mode is
related to aerosol accumulation over urban/industrial regions located mainly
south and west of Belsk.
Preliminary results of the trajectory analysis based on HYSPLIT model suggest that
a significant portion of an aerosol inflow over Poland originates in the southern
neighboring countries including Czech Republic, Hungary and Slovakia. To enable
studies of the changes occurring in aerosols during their transport over Poland a
new atmospheric observatory is being prepared in a south-western Polish city of
Raciborz at a site of IGF’s seismological station. The new installation is being
designed to be fully automatic when completed with the main instruments
including a sun-tracking photometer and a single wavelength autonomous elastic
lidar (a ceilometer).
P4.31 Recent science from Auchencorth: Insights into PM events and pollutants
54
associated with them
MM Twigg, J Kentisbeer, M Coyle, SR Leeson, A Hoque, YS Tang, MR Jones, B
Langford, WJ Bealey, D Leaver, I Simmons, I Washbourne, M Vieno, CF Braban, E
Nemitz
Auchencorth Moss has a hourly resolution measurement of PM10 and PM2.5
inorganic composition, NH3, HCl, SO2 HNO3 and HONO trace gases and PM size
distribution. When combined with the measurements of trace gases the PM
measurements can lead to insights into the drivers of chemical composition and
long term average concentrations which are comparable with modelling work, for
example with EMEP4UK. Recently published mercury data are discussed in
relation to the PM measurements. A particular new focus is looking at how
episodic pollution events occur and how they are interpreted. Results from
intensive measurement carried out in 2012 plus some event studies are
presented. The first assessment of fluoride in rain measurements carried out as
part of the routine measurements will be presented.
P4.32 Long-term study of new particle formation In a coastal environment:
Meteorology, gas phase and solar radiation implications
Sorribas, M., Adame, J.A., Vilaplana, J.M., Córdoba-Jabonero, C., Olmo, F.J.,
Alados-Arboledas, L. and Gil-Ojeda, M.
New particle formation (NPF) has been investigated at a coastal background site
in the South-western Spain over a 4-years period, using a Scanning Particle
Mobility Sizer (SMPS). The goals were to characterize the NPF and to investigate
their links with meteorological, gas phase (O3, SO2, CO and NO2) and solar
radiation (UVA, UVB and global) for event and non-events days. A methodology
to identification and classification of the NPF was implemented, being inputs the
wind direction and modal concentrations. NPF events showed a frequency of 24%
on total days. The mean duration was 9.2±4.2 hours. Contrary to previous studies
in other locations, the NPF frequency reached its maximum in cold seasons
around 30% of the days, and the lowest was in July with only a 10%. The seasonal
wind pattern was the most important parameter controlling the NPF frequency.
The mean formation rate was 2.2±1.7 cm-3 s-1, showing maxima in the spring
and early autumn and minima during the summer and winter. The mean growth
rate was 3.8±2.4 nm h-1 with higher values from spring to autumn. The mean
formation and growth rates and theirs seasonal evolutions are in agreement with
previous observations at continental sites in Northern Hemisphere. A NPF
classification in different Classes was carried out to explore the effect of synoptic
and regional-scale patterns on particle formation and growth. Results show that
under breeze regime, the temperature indirectly affects the NPF events. Higher
temperature increases the strength of the breeze recirculation favouring the
gases accumulation and subsequent NPF appearance. Additionally, the role of
high relative humidity inhibiting the NPF was evinced during synoptic scenarios.
The remaining meteorological variables (RH), tracers gases (CO and NO), solar
radiation, PM10 and condensation sink had a moderate or high connection with
both formation and growth rates, depending on the Class event.
P5.33 Comparison of EC, OC and OCx fractions at Prague-Suchdol and Košetice
background sites during heating and non-heating season
Petr Vodička, Jaroslav Schwarz, Vladimír Ždímal
55
Parallel measurements of elemental and organic carbon (EC and OC)
concentrations in the atmospheric aerosol were performed at the Czech
background site Košetice (rural environment) and at Prague-Suchdol urban
background site during heating (15 February – 1 April 2010) and non-heating (27
May – 30 July 2010) seasons. Semi-online field OC/EC analyzers (by Sunset
Laboratory Inc.) were used for the measurements with two hour time resolution.
The results show seasonal and sites differences in the content of EC and OC.
Overall, the highest concentrations of both the EC and OC were found during the
heating season at the suburban site. Non-heating season gives similar
concentrations of the OC on both sites, however, slightly higher concentrations of
EC were measured at suburban site, probably due to higher traffic. Diurnal
variations well indicate rush hour peak of the EC at suburban site during both
measurement periods, while EC time trends at rural background site show almost
no characteristic peaks.
Moreover, an analysis of four OC fractions and pyrolytic carbon (PC) depending
on the volatility (OC1 – most volatile, OC4 – least volatile) was carried out.
Diurnal trends of OC fractions in winter show significantly higher concentrations
of the OC1, OC4 and PC fraction at suburban site, however, urban OC1-OC4
concentrations in summer are much more similar to rural site. Therefore, detailed
analyses of OC fractions demonstrate the significant anthropogenic effect of
specific OC fractions on urban environment.
13:00-14:30 Lunch break
ACTRIS General Assembly I
Thursday, 12 June, 14:30 – 15:30
15:30-16:00 Coffee break
ACTRIS General Assembly II
ACTRIS SSC-AB
Thursday, 12 June, 16:00 – 18:00
Oral session S5: Climatology and Trends
Friday, 13 June, 09:00 – 09:30
09:00-09:30 ACTRIS-2
Presentation of the project & discussion (part II)
G. Pappalardo / P. Laj
Friday, 13 June, 10:00 – 12:00
Chairs: Anthony Illingworth, Cathrine Lund Myhre
Keynote presentation
(9:30-10:00)
AERONET program
Brent Holben (NASA-GSFC, USA)
S5.O1 (10:00-10:15) Long-term aerosol number size distribution measurements in Eastern
56
Mediterranean Nikolaos Kalivitis, Giorgos Kouvarakis, Aikaterini Bougiatioti, Iasonas Stavroulas, Alfred Wiedensohler and Nikolaos Mihalopoulos
Aerosol number size distributions have been measured at the environmental
research station of University of Crete at Finokalia, Crete, Greece (35˚20΄N,
25˚40΄E, 250m a.s.l) on a continuous base since 2008 in the frame of EUSAAR and
ACTRIS projects. The Finokalia station is the only station in Eastern Mediterranean
that size distribution measurements are taking place on a continuous basis during
both projects and is considered as a reference station for the region. The Eastern
Mediterranean is a cross-regional hotspot and its atmosphere is a complex
environment affected greatly both by long range transport processes from
different aerosol sources surrounding the region, namely marine, anthropogenic
from continental Europe and desert areas from northern Africa and from local
processes greatly affected by Intense photochemistry and sea-atmosphere
interactions. Longstanding monitoring and characterization of atmospheric
aerosols at Finokalia are of great importance for the whole region.
S5.O2 (10:15-10:30) Identification and monitoring of Sahara dust: An inventory representative for central Europe since 1997
H. Flentje, C. Beck, M. CollaudCoen, J. Cyrys, J. Gu, and W. Thomas
A daily catalogue of Sahara dust (SD) events at the Hohenpeißenberg Global
Atmosphere Watch (GAW) station (47.8°N, 11.0°E, 980 m a.s.l.) is presented from
15 years in-situ surface aerosol measurements. We identify Sahara dust particles
from the chemical composition, particle volume distribution and optical
properties of ambient particles. The detection skill is evaluated with data sets
from neighboring stations and aerosol model analyses and is comparable to that
of a Positive Matrix Factorization.
High daily Ca2+ concentrations combined with enhanced alkalinity and large
coarse particle mode volumes are identified as specific indicators for SD
admixture in Central Europe, while the specificy of spectral absorption is
unexpectedly small. On average, SD is detected in 5 to 15 Sahara dust events
(SDE)/yr covering about 10-40 days/yr in the boundary layer (BL). The frequency
of SDE is height-independent in the BL but the signature becomes less clear at
lower levels. It exhibits a clear seasonality with maxima in spring and autumn but
no significant long-term trend. With a total 228 SD days observed in the lower BL
from 1997 to 2012, 78/96/42/19/9/4/2 SDE lasted for 1/to/7 consecutive days.
On only 139/122/88/37 of 241 days, the SDE at Hohenpeißenberg extended as far
as to the 250 km distant Swiss Jungfraujoch station. Wet deposition of Ca2+ at
the surface is weakly correlated (R2=0.06) with the SDI and yields an average
annual Ca2+ imission of 0.22±0.04 g/m²yr, about 40% of which is due to SD. The
majority of outstanding weekly iron and aluminium depositions are associated
with SDE. The contribution of Sahara dust to the average PM10 load accounts to
0.5±0.1 µg/m³ (» 5%), but all threshold exceedances according to European
legislation (daily PM10 > 50 µg/m³) at Hohenpeißenberg are due to Saharan dust.
10:30-11:00 Coffee break
S5.O3 (11:00-11:15) Troposphere aerosols and long-term variations of cloud covering at Abastumani Goderdzi Didebulidze and Maya Todua
In Caucasus region, like other locations, the aerosols in troposphere and lower
stratosphere are both of local origin and a result of global transfer. Periodically
57
there are observed dust intrusions from other regions like Sahara, as well as
volcanic eruptions and forest fires. The lower atmospheric circulation in Caucasus
has its own peculiarities. Aerosols, if not accompanied by rain, are promptly
transported through the region. Abastumani is one of the favorable observation
locations, almost free from anthropogenic pollution. We studied long-term inter-
annual distributions of clear days and nights in Abastumani from continuous
atmospheric observations during 1957-1993. The data demonstrated that the
maximum number of cloudless days occur in August, while for cloudless nights it
appears in September, which maybe is unusual since aerosol concentration in
August is quite high. During geomagnetic disturbances, occurring mostly at
maximum solar activity phase, the greatest number of cloudless days moves to
September, which indicates the influence of cosmic factors on cloud covering. The
observed long-term trends of the mean seasonal planetary geomagnetic Ap index
for cloudless days and nights in summer also suggest the cloud cover coupling
with climate change. The comprehensive study of meteorological parameters and
lidar data in this region should be important for understanding regional and
global peculiarities of current climate change.
S5.O4 (11:15-11:30) Long term trends in aerosol optical characteristics in the Po Valley (IT) J.P. Putaud, F. Cavalli, S. Martins dos Santos, and A. Dell’Acqua
Aerosols properties have been monitored by ground-based in-situ and remote
sensing measurements at the station for atmospheric research located in Ispra on
the edge of the Po Valley for almost one decade. In-situ measurements are
performed according to Global Atmosphere Watch recommendations, and quality
is assured through the participation in regular inter-laboratory comparisons.
Sunphotometer data are produced by AERONET. Data show significant decreasing
trends over 2004 – 2010 for a number of variables including particulate matter
(PM) mass concentration, aerosol scattering, backscattering and absorption
coefficients, and aerosol optical thickness (AOT). In-situ measurement data show
no significant trend in the aerosol backscatter ratio, but a significant decreasing
trend of about -0.7 ± 0.3% in the aerosol single scattering albedo in the visible
light range. Similar trends are observed in the aerosol single scattering albedo
retrieved from sunphotometer measurements. Correlations appear between in-
situ PM mass concentration and aerosol scattering coefficient on the one hand,
and elemental carbon (EC) and aerosol absorption coefficient on the other hand,
however, no increase in the EC/PM ratio was observed, which could have
explained the decrease in SSA. The application of a simple approximation to
calculate the direct radiative forcing by aerosols suggests a significant diminution
in their cooling effect, mainly due to the decrease in AOT. Applying the
methodology we present to those sites where the necessary suite of
measurements is available would provide important information to inform future
policies for air quality enhancement and fast climate change mitigation.
S5.O5 (11:30-11:45) Validation of CALIPSO Level 2 aerosol profiles by EARLINET correlative measurements L. Mona, N. Papagiannopoulos, G. D’Amico, A. Giunta, A. Hiebsch, U. Wandinger, A. Apituley, L. Alados-Arboledas, D. Balis, A. Chaikovsky, A. Comeron, F. De Tomasi, V. Freudenthaler, I. Grigorov, M. Iarlori, H. Linnè, F. Madonna, A. Amodeo, A. Papayannis, A. Pietruczuk, F. Schnell, N. Spinelli, M. Wiegner and G. Pappalardo
58
EARLINET provides long-term, quality-assured aerosol data offering a unique
opportunity for the validation and exploitation of satellite-based aerosol
measurements. In particular, CALIPSO has been providing global aerosol/cloud
vertical profiles since June 2006. As long-term lidar network on continental scale,
EARLINET is the best candidate for the validation of aerosol and clouds
measurements provided by space lidars.
The good performance of CALIPSO and the absence of evident biases in the
CALIPSO raw signals were demonstrated through devoted comparison with
EARLINET ground based data applying an ad-hoc methodology. Case studies
analysis showed that the aerosol optical properties provided by CALIPSO (i.e.
Level 2 products) are typically in agreement within errors and uncertainties with
EARLINET measurements. In cases of high dust load, the aerosol extinction
retrieval can be affected by the influence of multiple scattering on space borne
lidar measurements. From Level 2 aerosol profiles, monthly mean profiles of the
aerosol extinction evaluated on 5° longitude x 2° latitude grid are provided as
Level 3 data. Once validated and assessed, these profiles would provide a suitable
database for climatological studies and comparison/assimilation in climate
models.
For this aim, all EARLINET observations related to CALIPSO overpasses collected
since June 2006 are compared to corresponding CALIPSO Level 2. This study
furthermore benefits from the availability of the 12-years long-term database of
EARLINET climatological data. About 150 profiles are compared. Apart from cloud
affected cases, we have on average a good agreement in backscatter profiles
comparison (Lev2) for all the stations. While larger discrepancies are observed for
extinction profiles. These can be related to the difference between the lidar ratio
values used in the CALIPSO retrieval and the measured ones. In particular,
significant differences are observed for mixed dust (Central Mediterranean area ),
polluted particles (Naples big city) and marine aerosols (Evora coastal site).
S5.O6 (11:45-12:00) Long-term surface ozone and aerosol physical variability at the Mt. Cimone WMO/GAW Global Station (2165 m a.s.l., Italy) L. Bourcier, P. Cristofanelli, A. Marinoni, R. Duchi, D. Putero, T.C. Landi, F.
Calzolari, M. Busetto, U.Bonafè and P. Bonasoni
Ozone (O3) and aerosol particles have a substantial impact on climate system and
air quality, especially over the Mediterranean basin where anthropogenic and
natural emissions as well as transport processes can significantly affect their
variability.
Surface O3 is monitored since 1991 at the global GAW station of Mt. Cimone
(CMN, 44° 11’ N, 10° 42’ E), while microphysical properties of aerosol particles
(scattering and absorption coefficients, number concentrations) are continuously
measured since 2008. Its location in the Mediterranean region, its physical
characteristics (highest peak of the Italian northern Apennines, 2165m a.s.l.),
makes it particularly suitable to study both the background conditions of the
Mediterranean/South Europe.
We analysed the long-term surface O3 variability at CMN from 1991 to 2011. The
measurements performed at this high-mountain observatory represent the
longest surface O3 record at a baseline site in the Mediterranean basin. Clear
positive linear trends in the monthly O3 mixing ratios were detected over the
period 1991 – 2011 with significant decreases of the seasonal O3 growth-rates.
Concerning the aerosol physical properties, the yearly and seasonal tendencies
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were investigated from 2008 to 2013 and showed a good agreement with the
trends observed at other European stations, even if it is hard to obtain statistically
robust indication for this relatively short time period. The monthly inter annual
tendencies are under investigation.
These information would be useful to better depict the long-term variability of
atmospheric composition of the Mediterranean basin and to better assess the
possible influence of anthropogenic and natural contributions.
Poster session P5: Climatology and Trends
Friday, 13 June, 12:00 – 13:00
P5.1 Winter/ Summer Vertical Aerosol Profiles in the Israeli coast using a
Ceilometer, Aeronet and Models
Smadar Egert, Leenes Uzan, Pinhas Alpert
The Earlinet spatial station spread currently reach Greece and Cyprus as the
eastern Mediterranean side, allowing accurate typing of the aerosol vertical
profiles. In Israel, several studies were done using satellite images and Aeronet
radiometric data that supplies the line integral of the aerosol features. However
Israel is equipped with several Ceilometers that were used for cloud detection and
their raw data was not collected. Although they are single wavelength Lidars,
they are located in various landscapes (near-seacoast, inland, mountain desert).
So access to their raw data is gradually built to monitor the layers features over
Israel and their relative evolution with time, as additional information to the
satellites and radiometric data. This data can serve as additional information to
the sophisticated stations of the eastern border of the Earlinet map (WP2 of the
Actris). Data analysis started last summer using the first available station located
on the middle of the Israeli shore.
The Israeli vertical temperature distribution during Summer was analyzed in the
past mainly by using a profiler located on the shore and the 7km inland Radio
sonde (00:00, 12:00 GMT). The summer climate is usually governed by the
synoptic Persian Troughs together with the land- sea interaction. In the morning
the fast rate of earth heating creates thermals which inflate the marine inversion
aloft. This process is suppressed when the sea breeze penetrates the shore line,
decreasing the thermal energy, thus resulting in the subsidence of the mixing
layer height. It was shown that the decrease rate is connected to the depth of the
Persian through, and it becomes shallower and also starts at a later hour as the
distance from shore increases. A two years summer study using a Lidar and a
Ceilometer showed good correlation between them PBL height and the aerosol
vertical distribution with time in both instruments. The winter that was less
studied. The current period covers part of 2013 summer and the dry winter of
2014 that were unusual compared to a normal season including some eastern
wind events and very early Sharav phenomena.
The Ceilometer data was analyzed along with the AERONET data from the closest
station, as well as radio sonde data and the information of the Hysplit program
and weather models, in order to try and gain better understanding of the daily
aerosol patterns. Some examples will be shown.
P5.2 Comparison of ACSM measurements with off line and on-line techniques
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I. Stavroulas, A. Bougiatioti, N. Kalivitis, G. Kouvarakis, C. Theodosi, P. Nikolaou
and N. Mihalopoulos
Using a variety of analytical techniques, aerosol chemical and physical properties
have been continuously being monitored at Finokalia, Crete. The main
infrastructure deployed features an Aerosol Chemical Speciation Monitor (ACSM)
which measures organics, sulfate, nitrate, ammonium and chloride at a 30 minute
resolution time. Chemical composition of aerosols is also being monitored via
daily sampling on filters. Organic and Elemental Carbon (OC and EC) are
measured using a SUNSET analyzer, while [SO4-], [NH4+], [NO3-], [Cl-], [K+],
[Mg2+] are determined via Ion Chromatography (IC). Black Carbon mass
concentrations are monitored using a seven wavelength Aethalometer. Number
size distributions of ultrafine particles are recorded using a Scanning Mobility
Particle Sizer (SMPS), while the aerosol scattering coefficient is determined using
Nephelometers operating at both fine and coarse modes.
A comparison between the various techniques offers a valuable insight on the
properties of the Eastern Mediterranean aerosol population, while on the other
hand allows a thorough quality check of ECPL’s instrumentation at Finokalia. The
comparison will be presented, focusing on the time period in which the ACSM is
deployed at Finokalia, i.e from May 2012 to December 2013. The sum of ultrafine
particle mass concentrations measured by the ACSM and Aethalometer, namely
both refractory and non-refractory PM-1 particle mass concentrations, was in
good agreement with mass concentrations derived from the particle number size
distributions. In addition different species mass concentrations were in good
correlation with those acquired from filter analysis. ACSM organics exhibit almost
identical time variation to the OC measured from filters, while the same behavior
is observed when each one of the other ACSM measured species where compared
to ion concentrations from IC. Finally, aerosol surface, derived from the SMPS
measurements, was in accordance with the scattering acquired by the
Nephelometers.
P5.3 Results of a European inter-laboratory comparison study for the quantification
of biomass burning molecular tracers (levoglucosan, galactosan, mannosan) in
atmospheric particulate samples
S. Verlhac, A. Albinet, O. Favez, J.-L. Jaffrezo, Eva Leoz-Garziandia,M. Aurela, J.-L.
Besombes, M. Claeys, B. van Drooge, A. Hoffer, A. Kasper-Giebl, Y. Linuma, W.
Maenhaut, G. Matuschek, A. Piazzalunga, J. Sciare, E. Swietlicki
A European inter-laboratory comparison (ILC) for the analysis of levoglucosan and
its isomers (galactosan and mannosan) was organized within the European
ACTRIS project (WP3). The ILC was led by INERIS with the help of LGGE for quality
control analyses.
Four test materials were sent to the participants including two ambient air filter
samples (corresponding to high winter range concentrations), one laboratory
blank filter and one standard reference material (NIST SRM). The main purpose of
the ILC was to evaluate the analytical repeatability and reproducibility standard
deviations obtained by the participants using their own analytical methods and to
highlight any bias or influencing factor on the measurement quality of the
biomass burning molecular tracers.
Thirteen participants submitted their results and most of them obtained
satisfactory Z scores (Figure 1). Only two laboratories showed outliers for
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levoglucosan, and only one more also showed unsatisfactory results for
mannosan and/or galactosan. One laboratory showed a very high blank value for
levoglucosan. Only 3 laboratories showed standard deviations of repeatability
larger than 10 %. Standard deviations of reproducibility were about 20-25 % for
levoglucosan and mannosan, while values in the range 30-60 % were obtained for
galactosan. All the results obtained showed that the analytical procedure had no
influence on the quantification of levoglucosan and its isomers.
Expanded uncertainties obtained were satisfactory (e.g. < 52 % for levoglucosan)
and, for example, consistent with the one required for the measurement of
benzo[a]pyrene in ambient air PM10 (European Directive 2004/107/CE). Finally,
results of this ILC could be used as reference for the certification of the NIST SRM
1649b (urban dust).
P5.4 A Depolarization Lidar based Method for the Determination of Microphysical
Cloud Properties in Water Clouds near Cloud-Base
D.P.~Donovan, H-K~Baltink
The links between multiple-scattering induced depolarization and cloud
microphysical properties (e.g. cloud particle number density, effective radius,
water content) have long been recognized. Previous efforts to use depolarization
information in a quantitative manner to retrieve cloud microphysical cloud
properties have also been undertaken but with limited scope and, arguably,
success. In this work we present a retrieval procedure applicable to semi-
adiabatic liquid stratus clouds. Limiting the applicability of the procedure to
clouds whose structure resembles that of a semi-adiabatic model around cloud-
base (i.e. constant liquid-water constant (LWC) slope and constant number
density) allows us to reduce the cloud variables to two parameters (namely the
derivative of the LWC with height and the extinction 100 meters above cloud-
base). This simplification, in turn, allows us to employ a fast and robust inversion
procedure based on a look-up-table approach applied to extensive lidar Monte-
Carlo multiple-scattering calculations. In this paper we describe the theory
behind the inversions procedure and discuss its strengths and limitations. Several
validation case studies are presented where the results of the inversion procedure
are compared with simultaneous cloud radar observations. In non-drizzling
conditions it was found that the lidar-only inversion results can be used to predict
the radar reflectivity within the radar calibration uncertainty (2-3 dBz). Results of
a comparison between ground-based aerosol number concentration and lidar-
derived cloud base number considerations are also presented and discussed.
13:00 End of 4th
ACTRIS General Meeting
13:00-14:30 Lunch break
ACTRIS - 2 Writing Group
Friday, 13 June, 14:30 – 18:00
15:30-16:00 Coffee break
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