AMSU微波探测资料同化的质量控制方法概述

Overview on the Quality Control in Assimilation of AMSU Microwave Sounding Data

微波相比红外、可见光等卫星探测方式有能够穿透薄云的优点,同化微波探测资料能明显改进数值预报模式初始场。由于观测算子在云、降水粒子及性质复杂下垫面等因素影响下模拟辐射传输过程不准确,以及资料的观测误差较大等原因,实际同化应用时必须对微波探测资料加以认真筛选。为充分发挥探测资料作用并保证同化分析效果,在同化AMSU微波探测的研究中,很多机构和学者建立了散射指数、降水检测等质量控制方法,用来剔除观测算子不能准确模拟的观测。研究表明,资料同化过程中引入质量控制能起到改善同化效果,提高数值天气预报准确率的作用。但是,对于各种质量控制方法的原理和使用条件目前尚无完整的分析,使得各业务研究单位使用的质量控制方案差别较大。文章针对AMSU微波探测资料同化,在分析同化误差来源的基础上,总结了散射指数、降水概率、下垫面类型检测等质量控制方法,并简单讨论了质量控制的发展方向。

Comparing with infrared and visible radiation,microwave radiation has the advantage to penetrate into thin cloud.Satellite microwave sounding data make great contributions to numerical weather prediction （NWP）.The main usage of satellite microwave sounding data in NWP is to assimilate into the initial field.However,the observation operator used in assimilation of satellite microwave sounding data has large simulation errors under the conditions of cloud,precipitation and complicated land surface.Besides, the error of some microwave sounding data is also very large.Therefore how to choose microwave sounding data is a crucial issue in data assimilation.To guarantee the result of assimilation and use more sounding data,in the research of AMSU sounding data assimilation,many institutions and scholars have invented quality control schemes such as scatter index and rain detection to remove data that not well simulated by observation operator.Research shows that after using quality control in data assimilation,the assimilated output is improved and the accuracy of NWP is increased.But there is no detailed analysis on the theory and using condition of quality control so far,which makes the quality control used in research institutions quite different.In this paper,the source of the assimilation error and the principle of quality control are analyzed firstly.Then the quality control schemes used at the main operational NWP center are summarized. Finally,the future development of quality control is discussed briefly.