Assimilation of cloud affected radiances in NCEP GDAS
In the first part of this study, these TL and AD models are applied in the strong constraint in the GDAS to improve dynamic balance in the regions where moist processes are important. Differences in analyses before and after applying the moisture physics in strong constraint are compared and impacts in the forecast skills are discussed.
In the second part of this study, specific issues such as observations errors, bias correction, and quality control processes in assimilating cloudy radiances are discussed. Radiance data assimilation in cloudy regions requires rapid and accurate radiative transfer and radiance gradient models. For a vertically stratified scattering and emitting atmosphere, the Community Radiative Transfer Model (CRTM) was developed at the Joint Center for Satellite Data Assimilation (JCSDA). This CRTM is employed in this study to calculate radiances and Jacobians at various wavelengths for radiance assimilation under all weather conditions. Moisture physics model generated jacobians combined with CRTM generated jacobians are applied in GDAS system and preliminary impact studies are implemented.