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Representing the optical properties of black carbon in the integrated WRF-CMAQ system

Representing the optical properties of black carbon in the integrated WRF-CMAQ system. Francis S. Binkowski, UNC David C. Wong, US EPA. Introduction.

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Representing the optical properties of black carbon in the integrated WRF-CMAQ system

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  1. Representing the optical properties of black carbon in the integrated WRF-CMAQ system Francis S. Binkowski, UNC David C. Wong, US EPA

  2. Introduction The WRF-CMAQ system treats the effect of air quality on meteorology by calculating how the ozone and PM produced by CMAQ influences the surface energy budget and the atmospheric heating rates determined by WRF. The radiation calculation in WRF is done by RRTMG

  3. Motivation • Two current approaches to modeling the optical properties of particles • The Volume Mixture (VM) method • The Core-Shell (CS) method • What are the differences in the key variables

  4. Key Variables

  5. Computational Approach

  6. We use a Single Column Model (SCM) to examine the differences between the VM approach and the CS approach

  7. The inputs required for RRTMG in the SCM were calculated using a vertical profile of aerosol species mass concentrations and particle size distributions obtained from a CMAQ run. This case was downwind from a forest fire. Background gases & ozone are from the Mid-Latitude-Summer standard case.

  8. Fraction of Black Carbon

  9. Aerosol Optical Depth

  10. Single Scattering Albedo

  11. Aerosol Absorption Optical Depth (1-SSA)*AOD

  12. Column Asymmetry Factor

  13. Net Heating Rate

  14. Net Hearing Rate Lower Atmosphere

  15. AOD Profiles for Particular Wavelengths

  16. SSA profiles for Particular Wavelengths

  17. AF Profiles at Particular Wavelengths

  18. Conclusions • There are differences between the two approaches. • The CS method is more physically realistic and shows less absorption (Jacobson,2000) than the VM method. • The CS Method is the method of choice for WRF-CMAQ.

  19. Acknowledgments • This work was supported by the US EPA • The original codes for BHMIE and BHCOAT were obtained from Prof. Bruce T. Draine of Princeton University.

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