1. Aerosols in WRF-CHEM Eric Stofferahn George Mason University 2013-09-07_07:00:00 (UTC)

2. Part 1: Aerosols

3. What is an Aerosol? PM10 (10 µm) Small Particle (between a few nm and a few µm ) Composed of various chemical species (Sulfates, Nitrates, Sea Salt, Carbons, and more!)

4. Sources of Aerosol

5. Aerosol Effects Aerosols have several effects on climate Direct effect (Scattering and Absorption) Semi-Direct effect (Absorption -> Clouds) Indirect effects (Cloud Changes)

6. Aerosol Direct Effect

7. Aerosol Effects Aerosols have several effects on climate Direct effect (Scattering and Absorption) Semi-Direct effect (Absorption -> Clouds) Indirect effects (Cloud Changes) Equation Alert!!

8. Aerosol Semi-Direct Effect

10. Aerosol Effects Aerosols have several effects on climate Direct effect (Scattering and Absorption) Semi-Direct effect (Absorption -> Clouds) Indirect effects (Cloud Changes)

11. Homogeneous Nucleation

12. Kelvin Equation

13. Homogeneous Nucleation

14. Who will help? Aerosols!

15. Kohler Equations

16. Kohler Curves

17. Heterogeneous Nucleation Cloud Condensation Nuclei

18. Aerosol Effects Aerosols have several effects on climate Direct effect (Scattering and Absorption) Semi-Direct effect (Absorption -> Clouds) Indirect effects (Cloud Changes)

19. Aerosol Indirect Effects

21. Aerosol Effects

22. Part 2: WRF-CHEM

23. WRF Mesoscale Model  Limited Area (ICs and BCs)  Higher Resolution Dynamics Physics  Parameterizations

24. WRF

25. WRF-CHEM Coupling of Aerosol and Gas Chemistry to WRF Computationally Expensive! Choice of Aerosol modules including MOSAIC (bin) scheme

26. WRF-CHEM

28. Aerosol Life Cycle in WRF-CHEM

29. Coupling Key Term: Coupling Aerosol Properties ↔ Shortwave Radiation (Direct Effect) Aerosol Properties ↔ Cloud Microphysics ↔ TKE (Indirect Effects)

30. Part 3: WRF-CHEM Simulations

31. Appendix – Twomey Curve

32. Appendix – Ship Tracks

33. Numerical Model - WRF-CHEM WRF-CHEM is a mesoscale model that uses fully compressible nonhydrostatic equations The chemistry component contains a variety of modules for simulating aerosol direct, semi-direct and indirect effects and chemistry processes The aerosol scheme in use will be MOSAIC, which divides each species (sulfates, nitrates, sea salt, dust, black carbon, etc) into 8 size bins Lin microphysics includes water vapor, cloud water, rain, cloud ice, snow and graupel hydrometeors Other parameterizations: Grell cumulus, NOAH land surface model, Monin-Obukhov surface layer physics, Goddard shortwave radiation and RRTM longwave radiation

34. Numerical Model - WRF-CHEM Initialize Aerosol Fields with MOZART-4 Reanalysis Data 2.5 x 2.5 degrees, 28 vertical levels, updated every 6 hours