The optimal use of airs and amsu retrieved soundings on short-term weather forecasts

Earth atmosphere could be considered as a three dimension non-uniform fluid. It is critical to understand the current state in order to forecast future through the assist from numerical weather prediction (NWP) model. It is also challenge to get the current state of atmosphere by using conventional surface observation data especially over the ocean. On the other hand, the satellite observation could help to condition the three-dimensional atmospheric state globally in all-weather skies. Therefore, we would like to evaluate the impact from the use of satellite retrieved soundings in the NWP model. Various satellite instruments have different observational capability and limitation due to the characteristics of used channels. For example, microwave sounder (MW) observation has larger field-of-view (FOV) than infrared sounder (IR). However, MW may have the capability to reveal the atmospheric sounding below the cloud levels. We propose a series of experiments to quantify the optimal use of both MW and IR soundings in regional Weather and Research Forecasting (WRF) model through Three-Dimensional Variation (3D-var) data assimilation scheme. A heavy precipitation case during Mei-Yu season in June 2012 was chosen to evaluate the forecast performance. The preliminary results suggest both MW and IR soundings provide positive impact in forecast skill, and the best performance are using the clear-sky matched IR data with non-matching MV. Sensitivity studies were also conducted to exanimate the potential water vapor transportation mechanism in this case.