台风“麦莎”路径东折分析及NWP产品检验

THE ANALYSIS OF TRACK TURNING EASTWARD OF TYPHOON MATSA AND THE TEST OF NWP

本文利用气象常规资料、NCEP/NCAR再分析资料和数值预报产品(NWP)资料对0509台风"麦莎"路径两次明显东折(7日11时和8日23时)的原因进行了分析.并对NWP产品对麦莎路径的预报结果进行了检验。结果表明:麦莎路径主要受西太平洋副热带高压(副高,下同)与西风带环流的影响,两次明显东折与西风带环流的经、纬向调整及副高由块状变为带状有关;"副高南落"指标和广义李雅普诺夫稳定度判据中J_(32)的符号分别对应了麦莎的两次明显东折;麦莎中心气压和风力变化与台风的两次明显东折有很好的对应关系。另外,T213资料的涡度和位温预报场对台风的两次明显东折有一定的指示意义。NWP产品24 h内对台风路径的预报效果较好,但对台风的第二次东折预报较差。

The reasons of obvious turning eastward of 0509 typhoon Matsa are analyzed by using con- ventional meteorological data,NCEP/NCAR reanalysis data and numerical forecast product （NWP） data, and the abilities of NWP for forecasting the Matsa track are tested too. The result shows that the subtropi- cal high and westerlies are main factors to determine the Matsa track,and two obvious turning eastward of Matsa are related to the adjustment of subtropical high and westerlies. When subtropical high is accordance with ＂subtropical high moves southward＂ index,Matsa turns eastward firstly,and Matsa＇s second turning eastward occurs when J22〈0 according to Liapunov＇s stability criterion. Matsa＇s turning eastward corresponds to the changes of pressure and wind speed in the center of typhoon,and the vorticity and potential temperature fields of T213 data can give instructions to the two turnings eastward of Matsa . The result of NWP for forecasting the Matsa track is not so good,its remarkable ability of forecast seems to be confined within 24 hours. NWPS do not forecast the second turning eastward well.