FY-3第二代微波垂直探测118.75GHz频点资料同化应用问题研究

The secondary generation of microwave vertical sounding on board Chinese new meteorological polar orbiting satellite series FY-3 has not only almost the same capacity as that of sounder flown on the USA next generation of operational meteorological polar satellite, but also it is enhanced with extra eight channels at center frequency 118.75GHz in first internationally. In connection with the assimilation of FY-3 secondary generation of microwave observation in numerical forecast, key issues associated are addressed using the new 118.75GHz data with unique features. The work of below three aspects will be carried out: 1) The algorithm to estimate the satellite observation-based Cloud Liquid Water will be proposed. Its performance will be compared with the traditional scheme to evaluate the feasibility and accuracy. 2) The effect of CLW estimation as the predictor in bias correction, together with the application of a cloud emission and scattering index derived from double oxygen band observation and the estimated CLW　information in cloud examination will be investigated, to get the best one applied to the assimilation of secondary generation of microwave observation. 3) The platform with the capability of FY-3 secondary generation of microwave data assimilation will be set up by extending the GSI. The characteristics and rationality of satellite data enrolled in assimilation will be analyzed. Then the data value and potential contribution to numerical prediction of FY-3 microwave observation, including the new 118.75 GHz data will be valuated. The work could fix the main issues by which the use of FY-3 microwave data is restricted. It could push the use of Chinese meteorological satellite remote sensing in numerical forecast. Also, it will enhance the research capability and technological level of key issues associated with satellite data assimilation.

中国新一代极轨系列气象卫星FY-3搭载的第二代微波垂直探测不仅具备和美国新一代微波载荷基本一样的特性，更是在国际上首次增加了118.75GHz频点8个通道。针对FY-3第二代微波资料在数值预报中的同化，利用新增118.75GHz，聚焦解决应用中的关键问题，展开三方面工作：1）设计基于卫星观测的云中液态水CLW估计算法，和传统算法进行比对，验证可行性与准确度；2）在偏差订正中研究估计CLW作为订正因子的作用，试验导自双氧段探测云辐射和散射指数CESI和估算CLW信息的云检测方案，选择同化适用最优方案；3）以GSI为框架，构建第二代微波探测同化应用平台，分析同化诸环节卫星资料的特点和合理性，评估包括新增118.75GHz频点探测的微波资料对数值预报的应用价值和贡献潜力。工作可解决制约FY-3第二代微波资料同化的主要问题，促进中国气象卫星遥感资源在数值预报中的应用，提升关键技术的研发能力和水平。

卫星微波探测是对数值天气预报有着重要影响的一类卫星资料。搭载于中国FY-3D上的第二代微波垂直探测不仅具备和美国新一代微波载荷基本一样的特性，更是在国际上首次增加了118.75 GHz频点8个通道。但是，FY-3D的微波探测设计上又缺失了常用于质量控制的两个窗区通道。针对FY-3第二代微波探测资料在数值天气预报中的同化应用，本项目开展的主要研究内容和工作摘要如下：.1）FY-3D微波探测资料的同化应用。在解决了资料质量控制和偏差订正等环节问题基础上，FY-3D微波资料得到有效同化应用。FY-3D微波探测同化模块为上海台风所数值预报系统引入，应用表明对台风路径和强度的数值预报效果具有积极的改善作用。.2）基于FY-3D微波观测云中液态水和总可降水估算。FY-3D微波探测没有设计23.8和31.4 GHz通道，利用118.75 GHz频点，试验了双氧探测通道反演基于卫星观测的云液态水信息。另外，采用机器学习，建立了FY-3D缺失通道的重构算法，从而推算出云中液态水和总降水估算。.3）风云卫星仪器大气透过率计算模型构建和精度评估。针对风云卫星搭载仪器，实现了微波、红外高光谱、宽带红外和可见光4类探测仪大气透过率的快速计算，对模型精度进行了全面验证评估，为风云卫星探测数据的遥感应用和资料同化提供技术支持。.4）水成物辐射效应对卫星微波遥感的影响分析。通过在辐射传输求解中考虑云水、雨水、冰、雪和霰水成物辐射效应，研究了卫星微波遥感受水成物影响及其敏感度，同时分析了快速辐射传输模式CRTM和RTTOV结果间的异同。