Modulation of Low-Latitude West Wind on Abnormal Track and Intensity of Tropical Cyclone Nargis (2008) in the Bay of Bengal

作     者：李维维 王春在 王东晓 杨磊 邓奕 LI Wei-Wei;WANG Chunzai;WANG Dongxiao;YANG Lei;DENG Yi

作者机构：State Key Laboratory of Tropical OceanographySouth China Sea Institute of OceanologyChinese Academy of ScienceGuangzhou 510301 NOAA/Atlantic Oceanographic and Meteorological LaboratoryMiamiFloridaUSA 

出 版 物：《Advances in Atmospheric Sciences》 (大气科学进展（英文版）)

年 卷 期：2012年第29卷第2期

页      面：407-421页

核心收录：

学科分类：07[理学] 0706[理学-大气科学] 0816[工学-测绘科学与技术] 0825[工学-航空宇航科学与技术] 

基　　金：supportedby a grant from the Major State Basic Research Development Program of China(973Program)(No2011CB403500) the National Natural Science Foundation of China(NSFC)(NoU0733002) the Natural Science Foundation of Guangdong Province,China(No8351030101000002) 

主　　题：TC Nargis （2008） tropical cyclone westerly wind cross-equatorial flow Bay of Bengal 

摘      要：Tropical cyclone （TC） Nargis （2008） made landfall in Myanmar on 02 May 2008, bringing a storm surge, major flooding, and resulting in a significant death toll. TC Nargis （2008） displayed abnormal features, including rare eastward motion in its late stage, rapid intensification before landing. Using reanalysis data and a numerical model, we investigated how a low-latitude westerly wind modulated TC Nargis’ （2008） track and provided favorable atmospheric conditions for its rapid intensification. More importantly, we found a possible counterbalance effect of flows from the two hemispheres on the TC track in the Bay of Bengal. Our analysis indicates that a strong westerly wind burst across the Bay of Bengal, resulting in TC Nargis’ （2008） eastward movement after its recurvature. This sudden enhancement of westerly wind was mainly due to the rapidly intensified mid-level cross-equatorial flow. Our results show that a high-pressure system in the Southern Hemisphere induced this strong, mid-level, cross-equatorial flow. During the rapid intensification period of TC Nargis （2008）, this strong and broad westerly wind also transported a large amount of water vapor to TC Nargis （2008）. Sufficient water vapor gave rise to continuously high and increased mid-level relative humidity, which was favorable to TC Nargis’ （2008） intensification. Condensation of water vapor increased the energy supply, which eventuated the intensification of TC Nargis （2008） to a category 4 on the Saffir-Simpson scale.