摘要
The past few years have seen work on the maintenance and decaying mechanisms of tropical cyclones （TCs） over land. Statistic study has been on the landfall frequency and location of TCs and their maintenance, decaying, transition, intensification and dissipation for the past 32 years and that （1） the deeper water accumulates on land, the more favorable it would be for the maintenance of low pressures and vast lakes, and the surface of large rivers and large- sized reservoirs can slow down the decaying of TC lows, （2） the descending and intrusion of cold air from mid- and upper- tropospheric and warm advection from lower troposphere are responsible for TCs transition; and （3） after landfall, TCs tend to accelerate towards areas of intense convection to the northwest, etc. Being mainly numerical simulation and diagnostic analyses for cases covering much detail and depth, most of the studies cannot tell anything in common about how TCs maintain and decay over land. There has been little work on the difference of land track of TCs, which travel with the underlying surface changing from sea to land. The energy supply from the tropical ocean is severely reduced or completely cut off on the one hand, rough land surface is both a blocking and frictional force for TCs to dissipate their energy on the other. In fact, landfall TCs can either maintain for only a few hours and cover a distance of less than 100 km or stay active tbr more than 100 hours and go as farther away as a few thousand km inland. Why do they differ so much？ Why do TCs follow routes that differ dramatically when they land at or near the same sites with identical or similar underlying surface？ It is obvious that the environmental field is one of the essential factors for TCs after landfall. The aim of this paper is to discuss the effect of the environmental field on TCs track over land and to know whicch, synoptic systems or factors play key roles in it so as to provide basis for the forecasting of land track of TCs after landfall.
基金
A project from the Ministry of Science and Technology of China (2005DIB3j104)
