云迹风资料的三维变分同化及对台风预报的影响试验

ASSIMILATION OF CLOUD-DERIVED WINDS AND ITS IMPACT ON TYPHOON FORECAST

主要研究云迹风资料对三维变分同化分析场及台风预报的影响。首先分析了不同通道和层次的静止气象卫星云迹风产品的误差特征;然后,把云迹风资料放到GRAPES三维变分同化系统中进行同化,通过将不同观测类型资料的同化结果进行对比,探讨了红外通道和水汽通道云迹风资料对数值预报分析场的影响;最后,把同化后的分析场作为初始场,用WRF模式对2002年“森拉克”台风做24小时预报实验。结果表明,不同通道和层次的云迹风资料具有不同的误差特征;云迹风资料可以提高分析场和预报场中风压场的质量;而且在台风预报试验中可以更准确地预报台风的路径和降水。

In order to find the impact of cloud drift winds on variational data assimilation system and to provide reference for operational forecast of tropical cyclone, firstly errors of water vapor winds and infrared cloud drift winds in different levels have been analyzed in this paper; then, cloud drift winds of geostationary meteorological satellites-GMS 5 have been added in the GRAPES three-dimensional variational data assimilation system with radiosonde data. The impact of water vapor winds and infrared cloud drift winds in NWP have been checked by comparing and analyzing the result of assimilation. With the NWP initial field attained by the assimilation, the process of typhoon Sinlaku has been forecasted on 7 September 2002 through the WRF model. It was found that cloud drift winds of different channels and levels have different standard deviations. Cloud drift winds have the potential to improve the quality of analysis field and increase the accuracy of track and precipitation forecast of tropical cyclone.