热带气旋的登陆及其与中纬度环流系统相互作用的研究

TROPICAL CYCLONE LANDFALLING AND ITS INTERACTION WITH MID－LATITUDE CIRCULATION SYSTEMS

中文关键词:  热带气旋  中纬度环流系统  相互作用

英文关键词:Tropical cyclone  Mid-latitude circulation systems  Interaction

中文摘要:

      热带气旋的主要灾害往往在登陆前后造成,登陆问题是当今热带气旋研究的重点。热带气旋与中纬度环流系统相互作用,不仅影响热带气旋的结构和强度变化,也对中纬度地区天气产生重大影响。西风槽强度的变化可使热带气旋的降水突然增幅30%.环境场的急剧调整常引起热带气旋运动突变,在弱环境场中,热带气旋的异常运动与非对称结构关系紧密。中纬度系统对热带气旋的非对称结构有重要影响。另一方面,热带气旋向极移动过程中携带了大量可供中纬度地区降水的水汽,在气旋性切变的环境场中,热带气旋还向环境场输送能量,并激发和增强中纬度气旋性环流系统的发展,触发严重的灾害性天气。热带气旋有时也会截断低纬向中纬度的水汽输送及中纬度波动的能量频散,95%左右的南海热带气旋对梅雨有显著影响,其中约86%的热带气旋会导致梅雨减弱中断甚至结束。

英文摘要:

      Great variation in structure/intensity of tropical cyclone(TC) usually occurs around the period of TC landfalling. Much important processes would be its interaction with mid-latitude circulation systems (MLCS).Such interaction would affects not only TC but also the weather in certain ares in mid-latitude. TC vertical wind shear appears tilt influenced by midlatitude circulation systems,and part of warm air of TC will be dispersive,the surface pressure will rise and the TC intensity will get weaked. There will be some supper cloud cluster and eyewall vortex within TC influenced by trough in westerlies (TW),and the TC precipitation will be amplified by 30% abruptly if the TW intensity increases. The TC unusual movements are closely related to adjustment of MLCS and the TC asymmetric structure affected by MLCS. A great deal of water vapor enters the mid-latitude region along with TC polarward drifting,carrying mass energy from TC to the cyclonic shear in MLCS,which is favorable to the enhancement of the MLCS and appearance of heavy rain. On the other hand,TC could cut off the water vapor transportation channel from low to mid-latitude. About 95% of TCs of South China Sea have remarkable effect on MeiYu weakening and about 86% of TCs can interrupt or cease the MeiYu rainfall. This paper discusses the interaction between TC and MLCS as well as the relevant issues concerned.