FY-3A微波资料在“莫拉克”台风预报中的同化试验

我国新一代极轨气象卫星FY-3A于2008年5月26日发射成功,携带的微波垂直探测仪与NOAA系列卫星的ATOVS性能相似。为研究微波垂直探测仪资料在台风数值预报中的作用,实现我国FY-3A卫星的微波探测资料的直接同化,达到改进台风预报的目的,利用FY-3A微波探测资料,以WRF-3DVar系统为基础,针对2009年第8号台风"莫拉克"路径和强度预报,开展数值预报直接同化技术研究。试验结果表明,直接同化FY-3A微波资料对数值模式初始场改进要优于仅仅同化常规观测资料,对缺乏观测资料的海洋上改进尤为明显,模式初始场更加合理地反映海上台风环流形势以及温湿条件,海上台风的模式初始位置也得到了校正;经过FY-3A微波资料三维变分直接同化后,区域中尺度模式对台风路径预报效果具有积极的改善作用。

EXPERIMENTS OF ASSIMILATING FY-3A MICROWAVE DATA IN FORECAST OF TYPHOON MORAKOT

China's new generation of polar-orbiting meteorological satellite FY-3A was successfully launched on May 26th, 2008, carrying microwave sounding units which had similar performance to ATOVS of NOAA series. In order to study the application of Microwave Sounding data in numerical prediction of typhoons, directly assimilate the microwave sounding data of FY-3A satellite, and improve typhoon forecasting, we conducted numerical predictions of track and intensity of typhoon Morakot (2009) and carried out research on direct data assimilation technology, based on FY-3A microwave sounding data and WRF-3DVar System. Results show that direct assimilation of FY-3A microwave sounding data improves the initial fields of a regional numerical model much more than assimilation of conventional observations alone, which is especially significant in the ocean where there is always lack of conventional observations. The model fields are more reasonable in reflecting the initial typhoon circulation as well as temperature and humidity conditions, and typhoon centre position at sea has also been adjusted. Through direct 3DVar data assimilation of FY-3A Microwave, the regional mesoscale model has positively improved the forecasting of typhoon track. FY-3A microwave data can efficiently improve the ability of numerical prediction of typhoons.