Evaluation of All-Sky GPM/GMI Radiances for Vardah Cyclone Event in Regional Data Assimilation System

The present study investigates statistical properties of radiance simulations at multiple frequencies using a regional mesoscale model. We run the RTTOV-SCATT model with DDA sector snowflake shape for frozen hydrometeors to account for realistic scattering at microwave frequencies. The input to RTTOV model is provided by the Weather Research Forecast (WRF) model at 15 Km resolution which includes vertical hydrometeor profiles and surface fluxes. Case study results for vardah cyclone (2016) is presented and analyzed. The Probability distribution function (PDF) of normalized observed minus background/first guess (O-B) was found to be close to Gaussian for low microwave frequency channels (24V & 37V) and the same was found to slightly peak for high frequency (89V and 183±3 V) channels. Results suggest the potential for simulation of GMI radiances in all-sky WRF data assimilation system.