热带气旋“芭玛”异常路径分析

Abnormal track of tropical cyclone "Parma"

为了分析导致"芭玛"路径异常的原因,采用NCEP再分析资料,分析2009年17号热带气旋"芭玛"的路径和强度、在移动过程中的大尺度环流背景及水汽输送特征,得出以下主要结论:"芭玛"路径分为5个阶段,其中有3个阶段的路径为异常;2次逗留阶段具有相似的环流形势,"芭玛"都处于鞍型场中,没有大尺度环境气流的引导作用,热带气旋与β效应相互作用所产生的β漂移(北偏西的移动)较小,"芭玛"仅受地转偏向力的影响,出现原地打转的异常路径;第3阶段2个热带气旋"互旋"期间,"茉莉"与"芭玛"之间的距离为1 208～1 435km,两者发生明显的腾原效应,导致"芭玛"向东南方向移动,而"茉莉"北上。在"芭玛"生命史的5个阶段,东亚夏季风强度相对盛夏而言大大减弱,但"芭玛"仍获得了充足的水汽供应,这也是其成为长生命史热带气旋的一个重要原因。

To analyze the cause of the abnormal path of ＂Parma＂,the national centers for environmental prediction （NCEP） reanalysis grid data were used to analyse ＂Parma＂ mobile path, the large-scale flow field and water vapor transport characteristics. ＂Parma＂ is 17th of the 2009 tropical cyclones. The results show that ＂Parma＂ path is divided into five stages, of which there are three stages of abnormal path. The circulation situations of two remaining phases are similar. ＂Parma＂ is in the saddle-type field, and there is no large steering flow. The interaction among the tropical cyclone and Beta induces 13-drift, and 13-drift is relatively small, so ＂Parma＂ is mainly affected by the geostrophic deflection force, stagnating or swing moving little. In the third phase of double tropical cyclones of ＂mutual rotation＂, the distance of ＂Jasmine＂ and ＂Parma＂ is between 1208 km and 1435 kin. Fujiwhara effect happens apparently between double tropi- cal cyclones, leading to ＂Parma＂ moving east-southernly and ＂Jasmine＂ going north. In the five stages of ＂Parma＂ life cycle, the East Asian summer monsoon intensity is weaker than midsummer, but the ＂Parma＂ obtains ample supply of water vapor, which is an important factor for ＂Parma＂ to become a long life cycle of tropical cyclone.