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 state size distributioncomposition 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 Pressure (hPa)

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 WildfiresExcluding Wildfires

Emissions [ g m -2 yr -1 ] [ g m -2 yr -1 ] Including WildfiresExcluding Wildfires

ECHAM5-HAM Optical Properties Including WildfiresExcluding 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 Lohmann et al. (1999) Lohmann (2002)

Evaluation of Number Concentrations Measurement data by courtesy of Andreas Petzold and Andreas Minikin German Aerospace Center (DLR) Campaign-composite vertical profiles of aerosol number-concentrations

HAM Size Refractive Index ECHAM5 Radiation Radiative 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 N 1, M SO 4 5 N 5, M BC, M OC 6 N 6, M DU 7 N 7, M DU 2 N 2, M SO 4, M BC, M OC 3 N 3, M SO 4, M BC, M OC, M SS, M DU 4 N 4, M SO 4, M BC, M OC, M SS, M DU NUCLEATION (r < µm) MODES IN M7 HAM - Aerosol Representation