Global Simulation of the Indirect Aerosol Effect With the ECHAM5 GCM

1. 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 • Dalhousie University, Halifax, Canada • NASA Goddard Space Flight Center

2. mixing state size distribution composition Requirements for Aerosol Models To Simulate Radiative Effects • Sink processes  global aerosol distribution • Direct radiative effects • Aerosol-cloud interaction

3. Sulfur Chemistry  MOZART Chemistry(Feichter et al., 1996) (Horowitz 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;...) • 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 Radiation Module(Boucher and Stier) Stratiform Cloud Microphysics - Aerosol Activation(Lohmann et al., 1999; Lohmann, 2002; Zhang et al., submitted;Lin and Leaitch, 1997; A.-Razzak and Ghan, 2000) The ECHAM5-HAM Aerosol Model ECHAM5( Roeckner et al., 2003)

4. 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

5. Evaluation in SCM Mode Single column studies with Lin and Leaitch (1997) approachfor Atmospheric Radiation Measurement Programme intensive observation period in March 2000 Pressure (hPa) Pressure (hPa)

6. Evaluation in SCM Mode Aerosol- and standard-version agree well with the observations

7. 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)

8. Emissions Seasonal distribution of GFED wildfire emissions for South America

9. Emissions Including Wildfires Excluding Wildfires

10. 0 0 0 0 0.2 0.1 0.1 0.2 2 2 1 1 10 20 10 20 Emissions [ g m-2 yr-1 ] [ g m-2 yr-1 ] Including Wildfires Excluding Wildfires

11. ECHAM5-HAM Optical Properties Including Wildfires Excluding Wildfires

12. Optical Thickness ECHAM5-HAM and MISR AOT (550 nm)

13. Effect on Solar Radiation Flux [ W m-2 ] [ %] Difference in solar surface flux (with Wildfires - without Wildfires)

14. 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%

15. 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

16. Acknowledgements • 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

17. Glaciation Indirect Aerosol Effect Warm Indirect Aerosol Effects Cloud albedo + _ Cloud cover and lifetime Lohmann et al. (1999) Lohmann (2002) + + _ Precipitation _ + + + Cloud droplets Mixed particles Ice crystals + + Cloud nuclei Aerosols Ice nuclei + + + Aerosol Microphysics Chemistry Emissions Aerosol Dynamics Aerosol-Cloud Interaction

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

19. HAM Size Composition ECHAM5 Physics Refractive Index Diagnostics Mie Calculation - Lookup Table Radiative Properties ECHAM5 Radiation Radiation Module

20. MODES IN M7 SOLUBLE / MIXED INSOLUBLE NUCLEATION (r < 0.005 µm) 1N1, MSO4 AITKEN (0.005 µm < r < 0.05 µm) 2N2, MSO4, MBC, MOC 5N5, MBC, MOC Mixing State: ACCUMULATION (0.05 µm < r < 0.5 µm) 3N3, MSO4, MBC, MOC, MSS, MDU 6N6, MDU COARSE (0.5 µm < r ) 4N4, MSO4, MBC, MOC, MSS, MDU 7N7, MDU HAM - Aerosol Representation • Resolve aerosol distribution by 7 log-normal modes • Each mode is described by three moments: • Number, Median Radius  Mass, Standard Deviation (fixed)