卫星微波遥感受水成物影响及其敏感度分析研究

Study on the Effect and Sentivity of Water Content on the Satellite Microwave Remote Sensing

对卫星微波遥感水成物辐射效应的理解在云参数反演以及数值预报中使用受云和降水影响卫星资料等诸多应用中都是十分重要的。使用快速辐射传输模式CRTM,通过中尺度数值模式WRF预报输出的水成物信息,分析了云水、雨水、冰、雪和霰5类水成物对卫星微波遥感的影响及水成物辐射效应给卫星微波观测计算带来的误差特征,设计敏感性试验研究了卫星微波遥感对水成物含量、有效粒子半径和垂直分布层次的敏感度。结果表明:卫星微波遥感在多个探测频率上受水成物的影响较大,云水和雨水的影响主要以增温为主,雨水的影响幅度要大于云水,在影响最大的AMSUA 2通道,云水和雨水的增温分别可达到8K和17K左右。冰、雪和霰散射效应对卫星微波遥感的影响则主要以降温为主;相比之下,霰的影响量级最大,雪次之,两种水成物对微波遥感影响最大的通道为AMUSB的2通道,可达到-18K和-9K左右,冰的作用微乎其微。卫星微波遥感探测通道对水成物含量的敏感与受水成物辐射效应影响对应一致。卫星微波遥感不受云水和冰水粒子有效半径变化的影响,对雨、雪和霰大降水粒子的有效粒子半径较为敏感。同时,敏感性和影响程度随探测频率的不同呈现出影响的复杂性。此外,卫星微波探测对水成物垂直分布层次的敏感性表现为对水成物敏感探测通道的变化,其中AMSUB 3~5通道对高层水物质,包括冰、雪和霰垂直廓线的变化最为敏感。

Understanding of the radiant effect of water content on the satellite microwave remote sensing is very important to the applications such as cloud parameter retrieve and the use of satellite data affected by cloud and precipitation in numerical forecast and so on.By using the Community Radiative Transfer Model(CRTM)with the output from numerical forecast model WRF,the effect and sensitivity of water content,including cloud water,rain water,ice,snow and graupel,on the satellite microwave remote sensing are studied.The characteristics of the simulation bias of satellite microwave remote sensing are analyzed.Also,the investigation of the sensitivity degree of the satellite microwave observation to the magnitude,particle radius and the vertical profile of water content is presented.The result shows that the satellite microwave remote sensing is greatly affected by the water content in several channels.The cloud and rain water mainly increase the brightness temperature.The effect of rain water is larger than that of cloud water.The largest temperature increment in AMSUA channel 2brought by cloud and rain water is 8Kand 17K,respectively.The ice, snow and graupel decrease the brightness temperature.The effect of graupel is the largest.The largest decrement in AMSUB channel 2is-18K.Ice has limited contribution to the temperature descreasing.The sensitivity of satellite microwave remote sensing to the magnitude of water content corresponds well with the radiant effect of water content. The satellite microwave observation is not sensitive to the effective radius of cloud and ice particle and the sensitivity of satellite microwave remote sensing is large to the effective radius of rain,snow and graupel particles.The sensitivity degree change has become complex with the frequency.In addition,the sensitivity of satellite microwave remote sensing to the vertical profile of water content is presented by the change of channel affected.AMSUB channels 3~5are the most sensitive to the vertical profile of water content.