Analysis and Development of Relationships between ATMS Scattering Indices and VIIRS Cloud Product based Liquid/Ice Water Path

Microwave radiances from the Advanced Technology Microwave Sounder (ATMS) instrument are assimilated within National Centers for Environment Prediction’s (NCEP) Finite Volume Cubed Sphere Dynamical Core (FV3) based Global Forecast System (FV3GFS). ATMS profiles impacted by precipitation result in degrading the quality of observations used in the assimilation. Profiles impacted by precipitation are hard to classify due to difficulties in identifying accurate thresholds for the onset of precipitation. In FV3GFS, ATMS profiles impacted by precipitation are currently identified using scattering indices computed based on the Advanced Microwave Sounding Unit (AMSU) channels. Several studies in the past have derived cloud liquid water path based thresholds to identify precipitating clouds. We use the Visible Infrared Imaging Radiometer Suite (VIIRS) cloud product to develop new relationships between scattering indices (based on ATMS channels) and VIIRS based liquid water path and ice water path. These relationships would potentially be effective in eliminating precipitation impacted profiles and we will also use these relationships to identify clear profiles. The effects of implementing these relationships in the FV3GFS quality control are tested by running FV3GFS simulations and analyzing the impacts on the model forecasting performance. This presentation would provide a summary of the major findings from the above analyses.