机载雷达资料同化及在台风数值模拟中的应用研究

To improve the accuracy of the model initial condition and Typhoon prediction, the popular method is assimilating observation data into Typhoon model background. While, Typhoon generates and develops over sea, and the observations over sea are very sparse. The airbore radar observation net is the only platform to obtain the high spatial and temporal data. The airborne radar horizontal scanned range perpendicular to the flight leg is rather limitted, and the attenuation of airborne radar reflectivity is serious. To the horizontal scanned range, we plan to set up a series of sensitive experiment to assimilate airborne radar radial velocity using ARPS 3DVAR, in order to study the selection of horizontal de-correlation scale for the spacial range. To the attenuation of airborne radar reflectivity, we plan to construct an attenuation correction system, and then to assimilate the attenuation-corrected airborne radar reflectivity using ARPS Cloud Analysis system. Finally, based on the solution of those two questions above, the impact of assimilating airborne radar radial velocity and (or) attenuation-corrected reflectivity on Typhoon prediction will be analyzed. We expect that when this project is done, the selection of horizontal de-correlation scale of assimilating airborne radar radial velocity can be solved, and the assimilation of the attenuation-corrected airborne radar reflectivity can be done. The ultimate goal to improve the prediction of Typhoon can be done when this project is done.

利用同化方法将观测资料同化到模式背景场中是提高台风数值模式初始场的准确度，提高台风数值预报水平的主要手段。台风生成、发展于海上，海上观测资料稀少，机载雷达是能够提供高时空分辨率观测资料的观测平台。机载雷达扫描范围在垂直于飞机飞行路径的方向小于台风的眼墙尺度，并且机载雷达的反射率因子存在严重的衰减问题。针对机载雷达扫描范围问题，本项目拟采用ARPS 3DVAR 同化机载雷达径向风资料，通过敏感性试验分析同化该资料的水平特征尺度的选取问题；针对机载雷达反射率因子衰减问题，拟建立适用于该资料的衰减订正系统，拟采用ARPS Cloud Analysis 系统同化订正后的反射率因子；在前面两步的基础上，分析机载雷达径向风和（或）反射率因子的同化对台风数值模拟的影响。预期本项目完成可解决同化机载雷达径向风水平特征尺度的选取问题，可实现同化订正后的机载雷达反射率因子。最终提高台风数值预报水平。

利用合理的同化方法将观测资料同化到模式背景场中，是提高台风数值模式初始场的准确度，以及提高台风数值预报水平的主要手段。台风生成、发展于海上，海上观测资料稀少，机载雷达是能够 提供高时空分辨率观测资料的观测平台。机载雷达扫描范围在垂直于飞机飞行路径的方向小于台风的眼墙尺度，并且机载雷达的反射率因子存在严重的衰减问题。针对机载雷达扫描范围问题，本项目采用了ARPS 3DVAR方法同化机载雷达径向风资料，通过敏感性试验分析同化该资料的水平特征尺度的选取问题；针对机载雷达反射率因子衰减问题，建立了适用于该资料的衰减订正系统，采用ARPS Cloud Analysis系统同化订正后的反射率因子；在前面两步的基础上， 分析机载雷达径向风和（或）反射率因子的同化对台风数值模拟的影响。本项目解决了同化机载雷达径向风水平特征尺度的选取问题，实现了同化订正后的机载雷达反射率因子。 提高了台风数值预报水平。