夏季西北太平洋热带辐合带的强度变化特征及其对热带气旋的影响  

THE INTENSITY VARIATION OF THE SUMMER INTERTROPICAL CONVERGENCE ZONE IN WESTERN NORTH PACIFIC AND ITS IMPACT ON TROPICAL CYCLONES

作　　者：曹西[1,2] 陈光华[1] 黄荣辉[1] 陈文[1] 

机构地区：[1]中国科学院大气物理研究所季风研究中心,北京100029 [2]中国科学院大学,北京100049

出　　处：《热带气象学报》2013年第2期198-206,共9页Journal of Tropical Meteorology

基　　金：公益性行业(气象)科研专项(GYHY201006021);国家自然基金国际(地区)合作与交流项目(40921160379);国家自然基金青年基金项目(40905024)共同资助

摘　　要：利用卫星资料和再分析资料讨论夏季6—8月平均热带辐合带(Intertropical Convergence Zone,简称ITCZ)的强度变化特征及其对热带气旋的影响。首先利用120～150°E,5～20°N区域平均的对外长波辐射(Outgoing Long-wave Radiation,简称OLR)定义一个夏季ITCZ强度指数,再根据这个指数划分ITCZ强弱年并进行合成分析和相关分析。结果表明:ITCZ强弱的变化与高中低层大气环流和前冬海温场有显著的关系,ITCZ强年往往伴随有副热带高压的偏北、偏弱,对流层低层出现气旋性距平风场,高层出现反气旋性距平风场,同时整个太平洋前冬的SST的分布呈现类似La Ni a的海温分布,而弱年正好相反。另一方面,ITCZ的对流强弱对热带气旋(Tropical Cyclone,简称TC)的发生和路径均有重要影响,在ITCZ强年,相应区域上的TC个数增多,同时TC路径更易于打转;而ITCZ弱年,TC个数减少,TC路径更易于向西北行。Based on the satellite data from National Oceanic and Atmospheric Administration and the NCEP/NCAR reanalysis data, the variation of the intensity of convection over Intertropical Convergence Zone （ITCZ） in summer and its impacts on tropical cyclones are studied. In this paper, an intensity index of ITCZ is proposed according to Outgoing Long-wave Radiation （OLR） in the region of（5 - 20 ~N, 120 - 150 ~E） in the western North Pacific. Then strong and weak ITCZ years are classified and different variables during the strong/weak ITCZ years are analyzed. The composite results show that ITCZ anomaly is connected to the general atmospheric circulation and SST distribution in the precedent winter. In the strong ITCZ years, the subtropical anticyclone weakens and shifts northward. And there is salient cyclonic anomaly at the low level and anticyclonic anomaly at the high level. SST patterns in the precedent winter resemble to those of La Nifia. However, it is opposite in the weak ITCZ years. The impact of the ITCZ anomaly on the tropical cyclone （TC） formation and track is also discussed. There are more TCs over the western North Pacific （120- 150 E, 5- 20 N） in the strong ITCZ years and there is a significant increase in the northward recurving TCs. In the weak ITCZ years, fewer TCs occur and the frequency of the northwestward track is higher.

关 键 词：气候学 统计特征 合成和相关分析 热带辐合带(ITCZ) 强度变化 热带气旋(TC) 

分 类 号：P463.1[天文地球—大气科学及气象学]