2002年20号热带风暴风场非对称研究

Dissymmetrical Wind Field Analysis of No.20 Tropical Storm in 2002

用实测资料分析了2002年20号热带风暴(下面简称TCTropicalcyclone)风场分布,结果表明:TC从扰动到成熟期,风速分布均不对称,强风区位于台风东北部。但当TC进入北部湾后,受地形影响,强风区位于台风东南部。随着TC的加强,强上升运动有向TC中心靠近趋势,上升最大值高度有上升趋势,TC进入北部湾后,上升及下沉运动均是加强,上升最大值仍出现在350hPa层附近,TC中心以北有强下沉运动。TC登陆后内区仍有强上升运动,上升最大值出现在500hPa层附近,TC北侧有深厚的下沉运动。TC有暖心结构,350hPa附近增暖最明显,最强水汽辐合出现在850hPa附近的南半圆内。

This paper used the observed data to analyse the wind field distribution of No.20 tropical storm in 2002 （named Mekkhala, acronymized as TC in the following）, and the research indicates that from its disturbance to maturity, the TC wind field is dissymmetrical, with the strong wind region in its northeast part. But when TC moves into the Beibu Gulf, affected by the landform, the strong wind region locates in its southeast part. With the strangthening of TC, the strong ascending movement has a trend of closing up to its center,and the greastest value of ascending height tends to ascend. But when TC moves into the Beibu Gulf, ascend both the is and sinking movements strengthen, and the greastest value of ascending appears in around 350 hpa, and north of the TC center there is an intense movement of sinkage. After the TC lands, its inner part still has an intense movement, of ascending, the greastest value of ascending appears in around 500 hpa, and its north side has a profound sinking movement. The TC is warm in the center, the most obvious warming process appears in around 350 hpa, and the strongest moisture convergence appears in the southsemicircle around 850 hPa.