0421号热带风暴"海马"登陆前后环境场对其移向和强度影响的分析

0421号热带风暴“海马(Haima)”于2004年9月13日12:00在浙江省温州市沿海登陆,登陆后迅速减弱为热带低压,20:00在浙江境内消失.本研究采用物理量诊断分析法,探讨该热带风暴登陆前后涡度场、湿焓场变化对其移向和强度的影响.结果表明,该热带风暴登陆后,涡度(ξ)明显减弱.涡度局地变化(ξ/t)值分布显示,风暴移动方向的后方,涡度减弱的趋势比前方涡度增大的趋势更剧烈;风暴有向其外围(ξ/t)正值中心(即涡度增幅最大)移动的趋势.该热带风暴登陆前、后,湿焓都增大,但登陆后湿焓增大趋势已大大减弱;风暴有向湿焓局地变化(E/t)正值中心移动的趋势,即向能量增强最大的方向移动.

Analysis of effect of environment field on moving direction and intensity of landing/landed No. 0421 tropical storm "Haima"

The No. 0421 tropical storm "Haima" landed over the coast of in Wenzhou City,Zhejiang at 12:00,13 Sep.,2004. It weakened to tropical depression immediately after landed,and vanished in Zhejiang at 20:00. By diagnostical analysis of by physical quantity,the effect of vorticity field and moist-enthalpy fieled on the moving direction and intensity of 0421 tropical strom was explored. The results indicated that the vorticity obviously weakened after the tropical storm landed. The distributions of the local changes in vorticity (/t) showed that the tendency of vorticity weakening in the rear is more obvious than the tendency of vorticity increasing in the front of the storm moving direction. The storm removed toward the heart of the positive value (the largest increasing) of the vorticity (/t).The moist-enthalpy increased totally before and after it landed, and the tendency of moist-enthalpy increasing weakened greatlly.It removed to ward the heart of the positive value of moist-enthalpy local changes (E/t),in other words,it removed to ward the direction of the largest screngthening of energy.