两次华南持续性暴雨过程中热带西太平洋对流异常作用的比较  

COMPARISON OF THE EFFECTS OF ANOMALOUS CONVECTIVE ACTIVITIES IN THE TROPICAL WESTERN PACIFIC ON TWO PERSISTENT HEAVY RAIN EVENTS IN SOUTH CHINA

作　　者：鲍名[1] 

机构地区：[1]中国科学院大气物理研究所季风系统研究中心,北京100080

出　　处：《热带气象学报》2008年第1期27-36,共10页Journal of Tropical Meteorology

基　　金：国家重点基础研究发展规划项目(2004CB418303);中国科学院知识创新工程领域前沿项目(IAP07217)

摘　　要：利用NOAA的外逸长波辐射资料(OLR)和NCEP/NCAR再分析资料以及华南地区台站降水资料诊断分析了热带西太平洋对流活动在2005年和2006年华南地区持续性暴雨发生的大尺度环流背景上的物理作用。分析表明:2005年6月17～24日华南持续性暴雨过程与热带西太平洋对流的10～25天低频振荡从150°E附近西传有关,持续性暴雨期间西太平洋副热带高压持续西伸的Gill型环流响应对应于传播到120°E附近强对流的低频间歇期;2006年5月下旬～6月中旬华南的持续性暴雨可能与热带西太平洋的双热带辐合带(ITCZ)南支对流带异常强盛有关,持续强盛的南支ITCZ使得115～135°E平均的局地Hadley环流最大上升中心位于0～5°S,菲律宾海附近区域上升运动的减弱有利于西太平洋副热带高压持续西伸加强。通过比较这两例典型的华南持续性暴雨过程发现,副热带高压在华南地区持续西伸是两次持续性暴雨发生的共同的大尺度环流背景,而热带西太平洋对流活动则通过不同的物理过程影响副热带高压的持续西伸。The different effects of anomalous convective activities in the tropical western Pacific on two persistent heavy rain events in South China in 2005 and 2006 are compared in this study. The data used consist of NOAA Outgoing Longwave Radiation （OLR） data, the NCEP-NCAR reanalysis and precipitation from meteorological stations in South China. Results show that the persistent heavy rain in 2005 was related to the 10-25-day westward propagation of convective activities in the tropical western Pacific from about 150 °E. The physical mechanism is interpreted as a Gill-type response of subtropical anticyclone westward extension during weak convective activities period over the Philippine Sea. Our researches also show that the persistent heavy rain in 2006 had longer period than that in 2005, and the subtropical anticyclone persists westward in the earlier summer which is possibly related to the lasting anomalous strong convective motion in the southern branch of Intertropical Convergence Zone （ITCZ） in the tropic western Pacific. The anomalous convective activities affect the local Hadley circulation over the western Pacific with anomalous ascending motion south of the equator and anomalous descend motion north of it, in favor of the westward extension of the subtropical anticyclone for a long time. Comparison between the two persistent heavy rain events indicates different physical effects of convective activities in the tropical western Pacific, though both effects are helpful to the subtropical anticyclone westward extension as a common character of large-scale circulation backgrounds for persistent heavy rain events in South China.

关 键 词：华南前汛期 持续性暴雨 热带西太平洋 对流活动 物理作用 

分 类 号：P434.4[天文地球—大气科学及气象学]