投稿时间:2019-09-21  修订日期:2019-10-25  点此下载全文
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陈耀登 大气科学学院 keyu@nuist.edu.cn 
沈洁 大气科学学院  
范水勇 中国气象局北京城市气象研究所  
王程 大气科学学院  
中文摘要:FY-4A星观测效率高、扫描速度快、观测频次高,标志着我国静止气象卫星的更新换代。为了推进FY-4A卫星资料在数值模式中的实际应用,本研究选择云导风产品作为研究对象,首先统计了FY-4A高层水汽通道和红外通道云导风的观测误差。进一步基于WRFDA(Weather Research and Forecasting Model Data Assimilation System)系统,利用默认观测误差和新观测误差进行了为期一个月的循环同化及预报试验,并分析了试验期间的台风预报效果。结果表明:FY-4A云导风产品的新观测误差存在明显的垂直结构特征;采用本研究统计的FY-4A云导风观测误差,能够在默认观测误差的基础上改善风场的分析和预报效果;试验期间的两个台风个例分析表明,新观测误差也能够减小台风路径的预报误差。
中文关键词:资料同化 FY-4A 云导风 观测误差
Study on Observation Error Statistics and Assimilation Application of FY-4A Satellite Atmospheric Motion Vector
Abstract:Data from FY-4A satellite has a higher temporal and spatial resolution than data obtained from FY-2 satellites, which indicates the development of China's geostationary meteorological satellites. In order to promote the practical application of FY-4A satellite data in the model and to investigate the impact of observation error on the assimilation and forecasting of atmospheric motion vector (AMV) from FY-4A, the research is carried out. Firstly, the observation errors of AMVs derived from high-level water vapor channel and infrared channel of FY-4A are calculated and analyzed. The vertical profiles show that compared with the default observation errors of the assimilation system, the new observation errors of the high-level water vapor channel decrease with height between 700hPa and 200hPa. And the new observation errors of the infrared channel are smaller below 800hPa than that above 700hPa where the vertical structural features are more pronounced. Secondly, a series of assimilation and forecasting experiments are carried out with default observation error and new observation error. According to the average RMSE profiles, results using new errors are significantly improved in the wind field compared with results using the default errors. At the same time, the height at which the RMSE of wind field has the maximum improvement corresponds to the height at which the number of observations is the largest. In addition, the new observation errors of the infrared channel influence wind filed more widely than that of high-level water vapor channel because data from infrared channel is distributed almost on each layer. Finally, the track and intensity forecast of typhoon “Hato” and “Pakhar” are discussed to further study the impact of observation error on forecasting. The results of the typhoon forecast indicate that the new observation error can significantly improve the track forecast and increase the accuracy of the intensity prediction to some extent.
keywords:Data assimilation, FY-4A satellite, Atmospheric motion vector, Observation error
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