台湾海峡区域热带气旋内核深对流特征分析

利用1996-2010年的卫星红外云顶亮温(TBB)资料,研究经过台湾海峡的热带气旋(TC)内核深对流活动特征。根据TC受台湾岛影响的大小分为远海区域、登陆前近海区域、台湾岛区域和海峡区域4个阶段。分析发现,穿越台湾岛进入海峡区域的TC内核结构趋于松散,深对流系统的总面积较远海和近海区域TC小,但深对流系统个数较前期显著增加,活动位置远离TC中心。海峡区域的水体虽然有利于TC内核深对流系统在一定程度上的恢复发展,但并不能明显促进极端强对流系统的加强发展。位于台湾岛和海峡区域TC的深对流系统活动具有明显的非对称特征,特别是海峡区域TC的热塔分布,在TC前进方向左后侧出现的概率最高,超过了半数。

Characteristics Analysis of Deep Convection in Inner Core of Tropical Cyclones at Taiwan Strait

The satellite infrared (IR) TBB data during 1996 and 2010 are analyzed to study the characteristics of deep convection in inner core of tropical cyclones (TC) at Taiwan Strait region. The TC are categorized into four different stages according to their distance to Taiwan island, including the far sea stage, coastal stage, over-Taiwan stage and over Strait stage. It is found that the inner core structure of TC tends to become looser as they move from far sea stage to over-Strait stage. The area of deep convection is much smaller at over-Strait stage than far sea or coastal stages, but the number of independent deep convection systems becomes more and occurs at a position further away from the TC center. The water body at Taiwan Strait is favorable for the recovery of deep convection in the inner core of TC passing over Taiwan island but not for the development of extremely deep convection systems (hot towers). The distribution of deep convection systems is significantly asymmetric for TC at over-Taiwan and over-Strait stages. Particularly, at over-Strait stage, over 50% hot towers appear at the left-rear quadrant as relative to the moving direction of the TC.