有云条件下HIRS/3资料的同化及其对“珍珠”台风的影响

Assimilation of HIRS/3 brightness temperature in cloud condition and its impact on Typhoon Chanchu forecast

中文关键词:  “珍珠”台风，HIRS/3红外通道，同化

英文关键词:Typhoon Chanchu, HIRS/3 infrared channel, Assimilation

中文摘要:

      卫星红外辐射资料直接同化容易受到云的影响，大量卫星资料在有云情况下无法直接同化， 其原因之一就是初始云结构难以获取，而云结构是同化系统观测算子的重要输入参数，缺乏 云的结构信息，观测算子无法模拟有云环境下的亮温。热带地区以及台风、暴雨等极端天 气系统与云密不可分，要改进卫星辐射资料特别是红外资料直接同化的效果，需要获得较高 精度的云三维结构。在GRAPES-3DVAR（Global and Regional Assimilation and Predicti on Enhanced System，全球/区域同化预报系统）基础上，结合WRF（Weather Research and Forecasting Model，天气研究和预报模式）对“珍珠”台风云结构的模拟，增加模拟的云参数作为GRAPES 3DVAR同化系统中RTTOV模式（fast radiative transfer model for TOVS，快速辐射传输模式）的输入参数，改进了有云环境下卫星资料直接同化的观测算子，研究了红外辐射资料直接同化的方法，并分析其对“珍珠”台风预报的影响。针对NOAA16（National Oceanic and Atmospheric Administration，美国国家海洋和大气管理局）的HIRS/3（High Resolution Infrared Radiation Sounder，高分辨率红外辐射探测仪3型）第4—8、10、13—19通道辐射亮温的同化试验表明，结合初始云结构信息改进同化系统观测算子，可以将红外辐射资料的观测信息同化到模式之中，改进台风温度、湿度结构，对短时降水预报有正面影响。

英文摘要:

      Satellite radiation data assimilation can be easily influenced by clouds, and huge amount of satellite data cannot be directly assimilated to numerical model in cloudy cases. One reason is that the initial cloud structure cannot be easily obtained, which is an important input parameter for an observation operator invariational system. Without the data of cloud structure, the observation operator cannot correctly simulate the brightness temperature in cloud condition. Because of the high cloud fractions in the tropics and the close links between clouds and extreme synoptic processes, such as typhoons and heavy rains, high accuracy three dimensional cloud structures are needed for the assimilating satellite radiation data, especially infrared channels. Based on the GRAPES 3DVAR（Global and Regional Assimilation and Prediction Enhanced System）and the simulated cloud structures of CHANCHU typhoon by WRF（Weather Research and Forecasting Model）, which are added to the RTTOV（fast radiative transfer model for TOVS）as input variables to improve the observation operator, the infrared channel brightness temperatures are assimilated into the numerical model and its impact to typhoon forecast are analyzed. Results show that while providing the initial cloud structures, some of NOAA 16 (National Oceanic and Atmospheric Administration) HIRS/3（High Resolution Infrared Radiation Sounder) channels, such as channels 4-8,10, and 13-19, can be assimilated properly, the temperature and moisture structure of typhoon can be improved, and the HIRS/3 infrared channels assimilation have positive impact on short term precipitation forecast.