水物质对云雨区卫星微波观测模拟影响

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

受云和降水影响卫星资料在数值天气预报中的同化应用对于进一步改善数值预报效果具有重要作用,这部分工作的开展要求快速辐射传输模式中能够较好地考虑各种水物质的辐射效应。使用美国卫星资料同化联合中心新近开发的快速辐射传输模式CRTM,通过中尺度数值模式WRF的预报输出提供水物质输入,分析水物质辐射效应对云雨区卫星微波观测模拟计算的影响。在WRF模式预报水物质的分布和天气系统配置合理并符合云物理基本特征的前提下,水物质辐射效应的考虑极大改善了卫星观测模拟的效果。结合卫星各通道探测特性,进一步分析各种水物质粒子对NOAA-16 AMSU A/B各通道卫星亮温模拟的影响和物理机理,定量统计各类水物质对各卫星观测通道亮温计算偏差和偏差贡献的权重大小。分析结果表明:快速辐射传输模式中,考虑水物质辐射效应为数值天气预报中云雨区卫星资料的同化应用提供了必需的基础条件。

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.