Global Simulation of the Indirect Aerosol Effect With the ECHAM5 GCM III LBA Scientific Conference...
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Transcript of Global Simulation of the Indirect Aerosol Effect With the ECHAM5 GCM III LBA Scientific Conference...
Global Simulation of the Indirect Aerosol Effect With the ECHAM5 GCM
III LBA Scientific Conference
Brasilia 28/07/2004
P. Stier (1), J. Feichter (1), S. Kinne (1),
U. Lohmann (2), J. Zhang (2), G. R. van der Werf (3)
(1) Max Planck Institute for Meteorology, Hamburg, Germany
(2) Dalhousie University, Halifax, Canada
(3) NASA Goddard Space Flight Center
• Sink processes global aerosol distribution
• Direct radiative effects
• Aerosol-cloud interaction
mixing statesize distribution composition
Requirements for Aerosol Models
To Simulate Radiative Effects
ECHAM5( Roeckner
et al., 2003)
Size-Dependent Dry- and Wet-Deposition(Ganzeveld et al., 1998; Slinn and Slinn, 1982; Feichter et al., 1996; ...)
Online emissions of Dust, Sea Salt and DMS(Tegen et al., 2002; Schulz et al., 2002; Kettle and Andreae, 2000;...)
Sulfur Chemistry MOZART Chemistry(Feichter et al., 1996) (Horowitz et al., 2003)
Aerosol Microphysics M7 (Vignati, Wilson, and Stier, JGR, accepted)
• Nucleation of sulfate particles• Condensation of sulfate on existing particles• Coagulation• Transfer from insoluble to soluble modes• Thermodynamical equilibrium with water vapour
Stratiform Cloud Microphysics - Aerosol Activation(Lohmann et al., 1999; Lohmann, 2002; Zhang et al., submitted;Lin and Leaitch, 1997; A.-Razzak and Ghan, 2000)
Radiation Module(Boucher and Stier)
The ECHAM5-HAM Aerosol Model
Aerosol-Cloud Coupling in HAM
Alternative schemes for aerosol activation:
• Empirical approach (Lin & Leaitch, 1997)
• Explicit activation (Abdul-Razzak et al., 1998; Abdul-Razzak and Ghan, 2000):
- Caveats: uncertainties of composition, e.g. for organics
Evaluation in SCM Mode
Single column studies with Lin and Leaitch (1997) approach
for Atmospheric Radiation Measurement Programme
intensive observation period in March 2000
Pre
ssu
re (
hP
a)
Pre
ssu
re (
hP
a)
Aerosol- and standard-version
agree well with the observations
Evaluation in SCM Mode
Global Simulations
• Global simulations with Lin and Leaitch (1997) activation scheme
in T63 resolution ( 1.8 x 1.8 on Gaussian grid) with 31 vertical levels
• ECHAM5-HAM nudged to ECMWF meteorology for year 2002
• Two simulations: with and without wildfire emissions
• Tropical wildfire emission inventory GFED for year 2002
based on methodology of van der Werf et al. (2003)
Emissions
Seasonal distribution of GFED wildfire emissions for South America
Emissions
Including Wildfires Excluding Wildfires
Emissions
0.10 1 10 [ g m-2 yr-1 ] 0.10 1 10
0.20 2 20 0.20 2 20 [ g m-2 yr-1 ]
Including Wildfires Excluding Wildfires
ECHAM5-HAM Optical Properties
Including Wildfires Excluding Wildfires
Optical Thickness
ECHAM5-HAM and MISR AOT (550 nm)
Difference in solar surface flux (with Wildfires - without Wildfires)
Effect on Solar Radiation Flux
[ W m-2 ] [ % ]
Discussion
Introduction of a global coupled aerosol-cloud climate model
• Prognostic treatment of CDNC and ICNC
• Aerosol activation schemes of intermediate and higher complexity available
Single column studies:
• Coupled aerosol-cloud model shows good forecasting skill
for observed hydrological parameters
Global simulations with focus on South American biomass burning season:
• Simulated AOT in good agreement with satellite measurements
• Wildfires dominant contributor to optical thickness and absorption
• Locally, wildfires decreases the solar surface flux by up to 20%
Outlook
Model development:
• Convective cloud scheme including microphysics and aerosol coupling
• Extended chemical composition and thermodynamics EQSAM/M7
• Extended parameterisation for organic carbonaceous compounds
Ongoing model evaluation:
• LBA measurements of great interest
Case studies:
• e.g. usage of measured activation spectra or CCN efficiencies
• single column studies
• Elisabetta Vignati and Julian Wilson, EC-JRC, Italy
• Erich Roeckner and the ECHAM developers team, MPI-Met, Germany
• Judith Hoelzemann, MPI-Met, Germany
• Part of this work was performed within the
EU project PHOENICS
PHOENICS Partners:
- University of Crete, Greece
- European Commission Joint Research Centre, Italy
- Max Planck Institute for Meteorology, Germany
- Max Planck Institute for Chemistry, Germany
- LSCE, France
- CNRS-LOA, France
- University of Utrecht, The Netherlands
- CNR, Italy
Acknowledgements
Precipitation
Cloud cover and lifetime
+
+
_
Aerosols
+Emissions
Cloud albedo
Cloud droplets
Cloud nuclei
+
+
+
Warm Indirect Aerosol
Effects
+
+Mixed particles Ice crystals
Ice nuclei
++
+
_
_
Glaciation Indirect Aerosol Effect
Aerosol-Cloud Interaction
Aerosol Microphysics Chemistry
Aerosol Dynamics
Lohmannet al. (1999)
Lohmann (2002)
Evaluation of Number Concentrations
Measurement data by courtesy of Andreas Petzold and Andreas MinikinGerman Aerospace Center (DLR)
Campaign-composite vertical profiles of aerosol number-concentrations
HAM
Size
Refractive Index
ECHAM5 RadiationRadiative Properties
Mie Calculation - Lookup Table
Composition
Diagnostics
ECHAM5 Physics
Radiation Module
Resolve aerosol distribution by 7 log-normal modes
Each mode is described by three moments:
Number, Median Radius Mass, Standard Deviation (fixed)
Mixing State:
AITKEN(0.005 µm < r < 0.05 µm)
ACCUMULATION(0.05 µm < r < 0.5 µm)
SOLUBLE / MIXED
COARSE(0.5 µm < r )
INSOLUBLE
1 N1, MSO4
5 N5, MBC, MOC
6 N6, MDU
7 N7, MDU
2 N2, MSO4, MBC, MOC
3 N3, MSO4, MBC, MOC , MSS , MDU
4 N4, MSO4, MBC, MOC , MSS , MDU
NUCLEATION(r < 0.005 µm)
MODES IN M7
HAM - Aerosol Representation