The Effect of Water Content on the Simulation of Satellite Microwave Observation in Cloudy and Rainy Area

Satellite data contribute to the improvement of numerical weather forecast accuracy greatly.In most current data assimilation systems, only clear-sky satellite data are used, but the observations in cloudy and rainy area have crucial information for the development and forecast of the weather system. Using satellite data affected by cloud and precipitation will be one of the effective methods to improve the accuracy of numerical forecast continuously. To achieve this target, the radiant effect modules of water content are being developed in both RTTOV and CRTM, which are two popular rapid radiant transfer models developed by EUMETSAT Satellite Application Facility on Numerical Weather Prediction (NWP SAF) and USA Joint Center for Satellite Data Assimilation (JCSDA), respectively. Using rapid radiant transfer model CRTM, the radiant effect of water content on the simulation of satellite microwave observations in cloudy and rainy area is analyzed.The water content input of CRTM is taken from the output of the regional mesoscale model WRF. Under the circumstances that the disturbance of water content output corresponds well with the weather system and physical characteristics, the simulation of satellite observations are greatly improved by the consideration of the radiant effect of water content. Deliberating on the physical mechanism of satellite observations, the effects of different kinds of water content on the simulation of different satellite observation channels are investigated. Quantitative statistics of the bias is performed and the influencing weight of each kind of water content on each channel of NOAA 16 AMSUA/B satellite is also calculated. These results are expected to facilitate understanding the error characteristics of simulated satellite microwave observations in cloudy and rainy area and accelerate using satellite data affected by cloud and precipitation in numerical weather forecast.