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Day 4 Lecture 1 Ground based networks – Paul Simon 1

DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

ATMOSPHERE REMOTE SENSINGValidation of Satellite Products

Paul SimonInstitut d’Aéronomie spatiale de Belgique

Acknowledgements:C. De Clercq, M. De Mazière, I. De Smedt, B. Dils, P. Gerard, J. Granville, F. Hendrick,J-C. Lambert, N. Theys, M. Van Roozendael, C. Vigouroux.

Day 4 Lecture 1 Ground based networks Paul Simon 1




Table of contents• 1. Introduction• 2. ESA Satellite observations

– GOME– GOMOS– MIPAS– SCIAMACHY

• 3. Ground based networks– NDACC– GAW

• 4. Validation principles• 5. Validation errors• 6. Atmospheric sensors validation

– GOME/ERS-2 & ENVISAT• 7. New generation of instruments



1. Introduction



ScienceKnowledge

Gaps(analysis,

validation,…)

ScienceKnowledge

Gaps(modelling,

assimilation,…)

KnowledgeGaps

Science &Applications

HOW TO BRIDGE THE GAPS ?

ComplementaryData

ComplementaryData

User’s needs

Observations Validated Data

Services

ScientificEnvironmental

StrategicPolitical

Socio-economicalCommercial

ProcessingInformation

ScienceKnowledge

Gaps(analysis,

validation,…)

ScienceKnowledge

Gaps(modelling,

assimilation,…)

KnowledgeGaps



ComplementaryData

ComplementaryData

User’s needs


Services


StrategicPolitical



ScienceKnowledge

Gaps(analysis,

validation,…)

ScienceKnowledge

Gaps(modelling,

assimilation,…)

KnowledgeGaps



ComplementaryData

ComplementaryData

User’s needs


Services


StrategicPolitical



ScienceKnowledge

Gaps(analysis,

validation,…)

ScienceKnowledge

Gaps(analysis,

validation,…)

ScienceKnowledge

Gaps(modelling,

assimilation,…)

ScienceKnowledge

Gaps(modelling,

assimilation,…)

KnowledgeGaps

KnowledgeGaps

Science &ApplicationsScience &

Applications


ComplementaryData

ComplementaryData

User’s needs


Services


StrategicPolitical



ComplementaryData

ComplementaryData

ComplementaryData

ComplementaryData

User’s needsUser’s needs


Services


StrategicPolitical



Towards an End-to-End Approach



Introduction

The global observing system must be designed to support the scientific questions inherent in

long-term atmospheric prediction.

Long-term validation of satellite products is mandatory to achieve this goal.



Observation Concept:

The Integrated Global Atmospheric Chemistry Observations (IGACO)Objectives

To ensure accurate, comprehensive global observations of key atmospheric gases and aerosols; To establish a system for integrating ground-based, in situ and satellite observations;To make the integrated observations accessible to users.



Satellites

Aircrafts

G-B Networks



The Integrated Global Atmospheric Chemistry Observations(IGACO)

A framework for the next generation…

The IGACO framework is an important strategy in integrating air chemistry observations including satellites and in bridging GAW to GEOSS, GCOS and the needs of the Numerical Weather Prediction community.



The existing observational system

A. Extensive ground-based measurements (in-situ and remote sensing) including balloons– Accuracy, long-term history, validation source, local/regional

relevanceB. Systematic aircraft measurements

– High-resolution tropospheric profiles,– Tropopause measurements, history

C. Satellite observations– Global coverage, uniform data quality

D. Chemical models and data assimilation tools– Integration, data analysis and exploitation



Station: Sodankylä. PI: Florence Goutail, CNRS

Continuity is essential for validation purposes

Satellite validation (Ozone)



2. Satellite observationsESA Satellite Sensors:

– Global Ozone Monitoring experiment (GOME)– Global Ozone Monitoring by Occultation of Stars

(GOMOS)– Michelson Interferometric Passive Atmospheric

Sounder (MIPAS)– Scanning Imaging Absorption Spectrometer for

Atmospheric Cartography (SCIAMACHY)



Global Ozone Monitoring Experiment (GOME/ERS-2)

• Launched in 1995• Nadir viewing mode• Leading role in retrieval and exploitation of products (e.g. O3, NO2, OClO, BrO,…), by DOAS analyses

• Evaluation of UV radiation intensity at the Earth’s surface



Atmospheric Species versus Instruments

Altit

ude (

Km)

03 H20 NO2 NO3 N2O CH4 HNO3 CO CO2 BrO p,T aerosol100

90

80

70

60

50

40

30

20

10

0

GOMOS

Troposphere

Stratosphere

O3 layer

Stratosphere

Mesosphere

MIPAS SCIAMACHYThermosphere

GOMOS Global Ozone Monitoring by Occultation of StarsMIPAS Michelson Interferometric Passive Atmospheric SounderSCIAMACHY Scanning Imaging Absorption Spectrometer for Atmospheric Cartography

ENVISAT Atmospheric Chemistry Mission



T(λ) = Iocc(λ) / Iref(λ)

Global coverageVertical profiles with1.7 km sampling

Self-calibration

Iocc(λ)Iref(λ)

star

sGOMOS occulation mode



MIPAS ViewingModes



Scanning Imaging Absorption Spectrometer for Atmospheric Cartography

- nadir, limb and solar occultation viewing modes;- 220-1750 nm + two IR channels;- surface : albedo, UV irradiance;- troposphere: O3, NO2, CO, BrO, CH4, H2O, HCHO, SO2, aerosols;- stratosphere: O3, NO2, N2O, CO, CO2, CH4, BrO, OClO, aerosols.

SCIAMACHY Viewing Modes



SCIAMACHY viewing modes



GOME & SCIAMACHY

Ground pixel resolution

40 x 320 km 16 x 32 km



Observing modes

Estimations for a tangent point around 30km altitude:

GOME: Nadir ⇒ ground pixel resolution

GOMOS: Occultation and limb ⇒ air mass at 3000 km

MIPAS: Limb (side & backward) ⇒ air mass at 3000 km

SCIAMACHY: Nadir ⇒ ground pixel resolution

Occultation ⇒ air mass at 3000 km

Limb (forward) ⇒ air mass at 3000 km



3. Ground Based Networks

- The Network for the Detection of Atmospheric Composition Change (NDACC) – (previously known as the Network for the Detection of Statospheric Change, ‘NDSC’)

- The Global Atmospheric Watch (GAW)



The Network for the Detection of Atmospheric Composition Change (NDACC)

Set up in the late 1980s (as NDSC):Dual goal of measurement and understandingProvide independent calibration/validation of satellites and

testing of models

• Endorsed by UNEP and IOC/IAMAS; • Incepted officially in 1991; • Major element of WMO’s GAW;• Major contributor to the worldwide atmospheric research effort,such as defined in Global Earth’s Observation System of Systems (GEOSS).



NDACCIt consists of a suite of globally distributed research stations providingconsistent, standardized, long-term measurements of atmospheric tracegases, particles, spectral UV radiation reaching the Earth’s surface, andphysical parameters.

Global set of more than 60 high-quality, remotesensing research stations

observing and understanding the physical and chemical state of the atmosphere

assessing the impact of atmospheric changes on chemical composition and on global climate

http://www.ndacc.org/



Observations are centered around the following priorities:

• Detecting changes and trends in atmospheric composition and understanding their impact on the stratosphere and troposphere;

• Establishing scientific links between climate and atmospheric composition;

• Testing and validating atmospheric measurements from satellites;

• Supporting field campaigns;

• Testing and improving theoretical and modelling work;

• Further our capability to forecast the future state of the atmosphere.

NDACC



NDACC Measurements Sites



Specific goals of NDACC

• To provide independent calibration and validation of space-based sensors of the atmosphere.

• To produce verified data sets for testing and improving stratospheric and tropospheric models.

NDACC data are ideally suited for satellite validation because they rely upon:

- Long time series- Rigorous quality control



NDACC Quality Control & Data Archiving

A commitment to data quality:

• Investigators subscribe to a protocol designed to ensure that archived data are of as high a quality as possible within the constraints of measurementtechnology and retrieval theory.

• Validation is a continuing process.• Instruments and data analysis methods are evaluated prior to NDAAC

acceptance and are continuously monitored throughout their use.• Formal intercomparisons are used to evaluate algorithms and instruments.• Data must be submitted to the central archive within one year of the

measurement.• Data go to anonymous ftp site when two years old.



NDACC:

• A key component of the IGACO initiative,

• Ground based measurement network with a long-term heritage,

• Conducting essential atmospheric observations,

• Providing correlative and validation data for satellite missions.

NDACC vs. IGACO



The NDACC: general organisation

Steering Committee

BREWER

DOBSON

UV

LIDAR

MWRO3S & aerosol

FTIR

DOAS

SAOZSatellites THEORY

Peers + Ex-officio



NDACC measurements

• Stratospheric temperatures• Total ozone• Ozone profiles• Compounds pertaining to ozone loss• ClO, OClO, BrO, HCl, HBr, ClONO2, CFC etc.• Greenhouse gases and water vapour• Stratospheric aerosols and polar stratospheric clouds• UV radiation



NDACC



Alpine Primary Station: Jungfraujoch



New Generation of instruments & measurements

MAXDOAS



3. Ground based networks (cont.)

The Global Atmospheric Watch Mission (GAW)



GAW Motivation



GAW Monitoring Themes



Global Stations in GAW



Stations registered for China (total: 13)Stations Station Type Coordinates Elevation (m, a.s.l.)

Gonghe Regional 36.27°N 100.62°E 2860 Hok Tsui / Cape d Aguilar Regional 22.22°N 114.25°E 60 Hong Kong Observatory Regional 22.31°N 114.17°E 65 Hong Kong University Regional 22.22°N 114.25°E 60 Kunming Regional 25.03°N 102.21°E 1917 Lhasa Contributing 29.40°N 91.03°E 3633 Linan Regional 30.30°N 119.73°E 138 Longfenshan Regional 44.73°N 127.60°E 310 Mt. Waliguan Global 36.28°N 100.90°E 3810Shangdianzi Regional 40.39°N 117.07°E 294 Xhianghe Regional 39.98°N 116.37°E 80 Yuen Ng Fun Regional 22.38°N 114.34°E 86

AntarcticaZhong Shan Regional 69.37°S 76.37°E 71



Mount Walliguan, P.R.C.



Estimated Global Ozonesonde Network: 2003



GAW Global Carbon Dioxide Network



Ten challenges for GAW (1)

(i) Maintaining long term measurements of quality in the current network

(ii) Establishing long term measurements of quality to improve global coverage, particularly in countries that are developing or in transition.

(iii) Developing collaboration between NHMSs and the chemical measurement community in some countries

(iv) Developing globally accepted calibration, quality assurance and standard operating procedures: costly and not high profile but essential

(v) Working with contributing partners that have networks as substantive as GAW to build a global network.



(vi) Developing World Data Centres that are comprehensive global repositories for high quality global observations of targeted GAW species.

(vii) Development of GAWSIS so that the GAW global network is accurately known.

(viii) Building a global aerosol monitoring network and integrated data analysis system in partnership with other organizations including satellite agencies.

(ix) Developing, with partners, an implementation plan for the Integrated Global Atmospheric Chemistry Observations (IGACO) strategy of IGOS

(x) Continue to build air quality management capacity in countries with megacities air pollution problems.

Ten challenges for GAW (2)

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