热带气旋"蒲公英"两次登陆过程的灾害与结构特征

2004年7月1~3日,热带气旋“蒲公英”自生成到影响浙江沿海地区期间,不仅持续时间长、强度大,移动路径长、变化较复杂,而且创下了近3年来台湾风灾损失的最高纪录,同时也给浙江等沿海地区造成了一定的经济损失。作者主要利用卫星云图资料、NCEP再分析资料,从宏观上对热带气旋“蒲公英”两次登陆过程中的强度及其引发的风雨灾害进行了分析。结果表明,“蒲公英”登陆台湾期间,东亚环流形势呈典型的鞍形场分布,有利于处于两高之间热带气旋“蒲公英”的维持和北上转向。而在其登陆浙江沿海地区后,浙江沿海地区处于较强的偏东气流中,“蒲公英”中心处于高空槽后,气流下沉以及缺少水汽和能量充沛供应使得其减弱为热带风暴。无论是其登陆台湾还是浙江沿海地区,台风垂直方向始终呈深厚气旋性涡柱结构,但中心附近低层辐散,中层辐合,不利于中心附近的对流发展。相反,台风外围螺旋云带内不仅中低层辐合,高层辐散,辐合层较深厚,且存在高湿和强上升运动,因而有利于对流云团的发展。对流云团发展强度的不同使得“蒲公英”两次登陆期间引发的风雨灾害明显不同。

The Analysis on the Structures of Typhoon "Mindule" During Its Twice Landing

The structures of a severe landing tropical cyclone "Mindule" from 0000 UTC 1 July 2004 to 0000UTC 4 July 2004 are investigated.By analyzing,it is revealed that: 1) The tropical cyclone(TC) "Mindule",which landed in Taiwan and Zhejiang,was very favorable for the occurrence of the gale and heavy rainfall.2) Under the favorable circulation in the middle-upper troposphere,warm core of the TC in the middle and upper troposphere maintain the characteristic of the tropical system.3) A strong wind coming from the South China Sea and the West Pacific,below 850 hPa accompanying with the TC was not only the favorable condition of the development and maintenance of the TC and embedded convective cloud cluster,but also the moisture source and heat energy transportation belt of the heavy rainfall.The lower-level inflow to the TC enhanced the warm,moist air transportation to the ascending motion area.4) The structure of TC "Mindule" was asymmetric.The TC was a cyclonic and wettest vortex below 200 hPa and the center of the vortex was almost vertical during its landing in Taiwan.There was a convergence zone and unstable stratification in the lower troposphere and a divergence zone in the upper troposphere near the center of TC.This structure is favorable to the intensification of ascending motion,the formation and development of strong convective systems and heavy rainfall.5) During the landing of TC "Mindule",the asymmetric distributions of temperature induce to interaction of the warm advection and cold advection,which was propitious to the occurrence of convection in the TC.