Scientific Advisory Committee Meeting, November 25-26, 2002.

Scientific Advisory Committee Meeting, November 25-26, 2002


Hartmut Grassl et al.: Interdepartmental Co-operation

Scientific Progress through Interdepartmental Co-operation

Hartmut Grassl

Max Planck Institute for Meteorology

Meteorological Institute, University Hamburg



OutlineMotivation

Results (Examples)

• Improving GCM parameterizations by LES modelling

• Complex planetary boundary layers measured and modelled

• Global distribution of semi-volatile organic compounds

Plans (Examples)

• Tropospheric aerosols and the climate of the North Atlantic region

• Persistent organic substances in and above the North Sea and

the Baltic Sea

• Evaluation of all MPI Met models by ENVISAT data



Motivation

•Most scientific progress originates from new data that falsify and subsequently improve models

•The experimental groups and the modellers have to co-operate

•In addition corporate identity is strengthened



LES for GCM Parameterizations (I)Chlond/Bäuml/Roeckner

Method:

1. Determine reduction factor for different cloud types using Large-Eddy Simulations and radiative transfer calculations

2. Implement correction factor into standard two-stream scheme, diagnosing cloud type from phase and cloud thickness

Goal:

Development of a radiative transfer parameterization in the ECHAM5 model which accounts for the effect of horizontal sub-grid scale cloud variability

Basis:

Effective Thickness Approach (Cahalan, 1994): Optical thickness of clouds is reduced by a correction factor



Geographical distribution of the mean winter albedo bias due to cloud inhomogeneity

Results:

• Albedo is reduced by 1.8 % in the global annual mean (corres-ponding to an increase of net SW radiation by 6.2 W/m2)

• Correction factors are in the range 0.4 1 for water clouds (depending on LWP), = 0.9 for ice clouds



LES for GCM Parameterizations (II)Chlond/Müller/Roeckner

Goals:

• advance the understanding of the physical processes that determine the thermal and dynamical state of the cloud-topped boundary layer

• evaluate and improve methods of representing shallow cloud systems in global climate models of the atmosphere

• produce comprehensive 4-D data sets using LESs

• use of LES data sets to investigate deficiencies in ECHAM using the Single Column Model (SCM) version as a test bed

• correct and improve parameterizations in ECHAM



LES vs SCM: Diurnal variation of LWP (FIRE)

Result: ECHAM-SCM produces a too shallow boundary layer and predicts a too low liquid water path but with a timing in phase compared with the observations



Observation and simulation of a double boundary layer over the Baltic Sea

Bösenberg/Jacob/Hennemuth

• During PEP in BALTEX a double-layered PBL was observed over the central Baltic Sea (Gotland) by lidar and other sensors

• REMO in the BALTEX version with 1/6° horizontal resolution is capable to simulate such structures

• The model results indicate that the upper layer is the advected PBL over land

• The occurrence of an elevated layer over the marine PBL further suppresses the vertical transport of sensible and latent heat from the surface layer into the free atmosphere

• Concerning PBL structure the Baltic Sea is rather a big lake than an ocean



Observation of the phenomenon



Simulation of the phenomenon



Profiles of Latent Heat Flux through Combination of an H2O-DIAL and a RADAR-RASS

Bösenberg/Peters/Wulfmeyer

Objective: Determine the vertical transport of water vapourin the boundary layer.

Approach: Eddy correlation technique using high resolution retrievals of vertical wind and water vapour.

Advantages: No assumptions on turbulence structure. Representative for large area.

Technique: RASS for vertical wind.DIAL for water vapour.



Profiles of Latent Heat Flux through Combination of an H2O-DIAL and a RADAR-RASS

Bösenberg/Peters/Wulfmeyer

P1 P2 P3 P4From Wulfmeyer, Atmos. Sci.

Gotland 12/13 September 1996



Vertical Structure of Aerosol Optical Properties over Europe

Bösenberg/Feichter

EARLINET• Systematic measurements of aerosol profiles at 22 stations in Europe• Quantitative lidar methods (Raman lidar, multi-angle method) applied• Quality controlled• Products: backscatter and extinction profiles, optical depth• Special measurements for diurnal cycle, Saharan dust, forest fires• 2.5 years of measurements • More than 10000 profiles

MODEL SIMULATIONS• Relaxation of the GCM towards

observed meteorology

• Calculation of the distribution of

the aerosol physical, chemical and

optical properties

• Atmospheric GCM ECHAM5-T63

(2ox2o horizontal resolution)

including aerosol microphysics



Intercomparison Observations - Model resultsRequirements for future cooperation

• Realistic intercomparison requires:

• Modelling of observable parameters:• Backscatter and extinction, optical depth• Calculation of statistical distribution• Improved representation of the PBL• Detailed comparison for typical situations

• Improved microphysical retrievals• Improved temporal coverage



Environmental fate of semivolatile organic compounds (SOCs), in particular persistent organic pollutants (POPs)

Lammel/Feichter

Scientific objectives: • Understanding the fate of those substances which migrate between compartments on large spatial scales• Validation of model tools used in decision making (national and international chemicals legislation / conventions)

Methodological achievements:• Multicompartment chemistry-transport model• Characterization of environmental fate by novel and appropriate indicators

Results obtained:• The persistence and long-range transport potential of SOCs are strongly (and more than expected) dependent on the location and the time of entry into the environment.



Environmental Fate as a Function of Location of Entry DDT emission from China (overall persistence Poverall = 10 years, effective spatial spreading SSeff = 750 km)

Ocean Atmosphere

Turkey (Poverall = 13 years, SSeff = 1900 km)



HOAPS



Direct and Indirect Aerosol EffectsOlaf Krüger, Johann Feichter

• Emissions: Africa (Sahara), USA, Europe

• Influence on ITCZ, NAO

• Correlations between cloud water/precipitation and

cloud albedo

• Evaluation of coupled global models with long satellite

time series (AVHRR, MODIS)



EXPOSURE TO PERSISTENT ORGANIC SUBSTANCES AND EFFECTS IN THE NORTH SEA AND BALTIC SEA ATMOSPHERIC AND AQUATIC ENVIRONMENTS

• INTERDISCIPLINARY:

• INTEGRATED: exposure (environmental) and effects (wildlife, humans) or: P+S+I #• GEOGRAPHIC FOCUS: German Bight (during the 1st phase)• PROCESS FOCUS: air-sea exchange (1st phase)• SUBSTANCE FOCUS: exploratory (1st phase)

Field Laboratory Modelling Atmospheric Sciences (MPI/MI) * * Oceanic Sciences (IfM) * * Chemical Analysis (IBM/FB13) *

Biological Analysis and Epidemiology (IHF)

* *

Public Health - Epidemiology (FB4) *

#D = driverP = pressureS = stateI = impactR = response



Conclusions

• Development of new remote sensing tools (sensors + algorithms) and LES modelling has reached a level that allows global and regional model evaluation and improvement

• Co-operation within the ZMAW will give us the capability of ecosystem model evaluation

• Our hypothesis: There is a connection between NH anthropogenic aerosol load and ITCZ as well as NAO



THE END

Scientific Advisory Committee Meeting, November 25-26, 2002.

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Transcript of Scientific Advisory Committee Meeting, November 25-26, 2002.