P12  Assimilating MODIS Aerosol-Sensitive Radiances using WRF-Chem and GSI

Lin, Hui-Chuan, and Zhiquan Liu, National Center for Atmospheric Research

Assimilation of the Moderate Resolution Imaging Spectroradiometer (MODIS) radiances has been developed within the National Centers for Environmental Prediction (NCEP)Gridpoint Statistical Interpolation (GSI) three-dimensional variational (3DVAR)data assimilation system using the Community Radiative Transfer Model (CRTM) as the radiative transfer model. The visible land surface reflectance in CRTM is derived from a look-up table with respect to the surface type and wavelength under the assumption of a Lambertian surface. The MODIS Bidirectional Reflectance Distribution Function (BRDF) product, MCD43, was used to better estimate the land surface reflectance for MODIS bands 1 through 7 to improve the CRTM forward radiance calculations. Weather Research and Forecasting/Chemistry (WRF/Chem) model with the Goddard Chemistry Aerosol Radiation and Transport (GOCART) module was used to provide the initial aerosol concentrations. The assimilation of MODIS aerosol-sensitive  x radiances was tested over a domain encompassing the continental United States.  The impact on aerosol analyses and subsequent forecasts was compared to that of assimilating retrived total aerosol optical depth. The results will be presented.