中文摘要：

对0509号台风“麦莎（Matsa）”登陆后长时间维持并轻度加强的过程进行了诊断研究，此过程涉及到多种因素。位涡分析表明，当中纬度西风槽东移，该槽底部分裂出的一个较小的正位涡中心与“麦莎”合并使“麦莎”的涡旋动能增强，而在9日之后“麦莎”与槽主体合并的阶段，槽区主要的正位涡中心与“麦莎”融合。动能收支分析发现，“麦莎”登陆北移过程中，高层的无辐散风穿越等高线将位能转换为动能这一过程较“麦莎”的整体加强为早，而辐散风是低层动能的主要来源。中低层天气尺度系统为积云对流的发展提供动能，而积云对流释放潜热又为高层动能的维持提供了帮助。将“麦莎”与北美“Agnes”飓风比较后发现，“麦莎”加强程度比“Agnes”较弱的原因之一，是高层的无辐散风把台风环流内的动能向环境输出，而“Agnes”飓风则是环境区有大量动能向台风环流区输送。分析水汽来源可知，在“麦莎”登陆期间及其后副热带和热带的两条水汽通道同时或分别为“麦莎”的积云对流提供了足够的水汽供应。

英文摘要：

A diagnostic study has been conducted on the sustaining mechanism of Typhoon Matsa （2005） which traveled northwards after landfall in Zhejiang Province with a Strong Tropical Storm intensity. The Ertel Potential Vorticity （EPV） analysis indicates that a small positive EPV anomaly at the bottom of the approaching mid-latitude trough was an important source of vorticity for the modest re-intensification of Matsa, the main positive EPV area merged with Matsa after 9 August, 2005. The kinetic budget anaysis shows that the kinetic energy （KE hereafter） generated by non-divergent wind component was prior to the intensification of Matsa, divergent wind component was the main kinetic energy source in the low-level, and the cumulus （sub-grid scale system） convection is another mechanism of upward kinetic energy transportation other than large scale ascending. The difference of KE transported by non-divergent wind between Matsa and Agnes （1972）, which experienced strong re-intensification, may be an important reason why Matsa did not reintensify greatly as Agnes. Traveling on land, there are two moisture channels providing abundant water vapor for the maintenance of Matsa.