温湿结构对南海低压发展影响的数值模拟研究

EFFECTS OF HUMIDITY AND TEMPERATURE STRUCTURE ON DEVELOPMENT OF TROPICAL DEPRESSIONS IN SOUTH CHINA SEA AND ITS NUMERICAL MODELING STUDY

摘要:

本文对比分析了两个南海热带低压,其中一个在24小时内发展为台风,而另一个不发展。通过几个改变初始场温、湿结构的数值试验的对比分析,指出低压区的温、湿结构对低压发展起着很重要的作用。中低层有深厚的高湿层存在,以及中低层有暖心存在,都有利于低压的发展加强,反之,中低层湿度较小或湿层较浅,以及暖心在高层而中低层无暖心,都不利于低压发展加强。同时,温、湿结构对低压发展的影响,可能主要是通过影响条件不稳定层的深浅和强弱,以及影响中低层的水汽能量供应,导致对流的发展趋势发生变化来实现的。最后指出,南海低压的发展对低压区的温度和湿度变化很敏感。

Abstract:

The compared analyses between two tropical depressions in South China Sea arc c by using the numerical model developed in Guangdong Institute of Tropical and Oceanic M logy and ECMWF data,one of which developed into a typhoon in 24 hours,and the other loped. The analyses show that their initial humidity and temperature fields have ent vertical structures, with the developing one has a deep high-humidity layer and a clearcored structure in the mid-lower troposphere, and the undeveloping one has not a warm structure in the lower troposphere and the humidity in the midlower troposphere is smaller.ral numerical tests, by changing their vertical structure of humidity and ien.-perauire in sion area, show that the humidity and temperature structure in the depression area play roles in the development of depressions. It is favourable to development of depres deep high-humidity layer or a warm-cored structure exist in the mid-iower troposphe versely, it is not favourable to the development of depressions when the humidity there is no warm-cored structure in the mid-lower troposphere. And these effects of temperature structure on the development of depressions occur most pdepth or strenth of conditional instable layer and vapor suply condition in theWhich leading to the change of convective development. Finally, the sensitivity ment of depressions in the South China Sea to the change of humidity and pression area is discussed.