热带西太平洋越赤道气流的年际变化对西北太平洋热带气旋生成的影响  

INFLUENCE OF THE INTERANNUAL VARIATION OF CROSS-EQUATORIAL FLOW ON TROPICAL CYCLOGENESIS OVER THE WESTERN NORTH PACIFIC

作　　者：冯涛[1,2] 沈新勇[1] 黄荣辉[2] 陈光华[2] 

机构地区：[1]南京信息工程大学气象灾害省部共建教育部重点实验室,江苏南京210044 [2]中国科学院大气物理研究所季风系统研究中心,北京100029

出　　处：《热带气象学报》2014年第1期11-22,共12页Journal of Tropical Meteorology

基　　金：国家公益性行业(气象)专项资助项目(GYHY201006021);国家重点基础研究发展计划项目(2010CB950403);国家公益性行业(海洋)专项资助项目(GYHY201005019-2)共同资助

摘　　要：利用美国联合台风预警中心的热带气旋（TC）数据以及日本JRA-25全球再分析等资料，分析了6—10月西太平洋上空3支越赤道气流的年际变化对西北太平洋（WNP）热带气旋（TC）生成数量和位置的影响。相关分析结果表明：越赤道气流主要影响140°E以东TC的生成数量，越赤道气流越强，在该海域生成的TC越多。通过合成分析讨论了越赤道气流强弱对WNP大气低层的风场、垂直风切变、高空散度、低层涡度以及OLR的影响，结果表明：在140°E以东的热带WNP，以上要素在越赤道气流偏强背景下的配置均有利于TC生成。同时，通过正压能量转换讨论了越赤道气流强弱对WNPTC生成的动力作用，指出在越赤道气流偏强年，季风槽东伸，东部的扰动容易从基本气流获得动能加强形成TC；在越赤道气流偏弱年，季风槽偏西，扰动动能增加的区域主要位于140°E以西，导致东部海域较少生成TC。此外，无论在越赤道气流强年或者弱年，在TC生成之前的2～4d均可发现有临近的越赤道气流突然加强的过程，这有可能是触发TC生成的动力因素之一。The influence of the interannual variation of cross-equatorial flow （CEF） on tropical cyclogenesis over the western North Pacific （WNP） is examined in this paper by using the tropical cyclone （TC） best track data from the Joint Typhoon Warning Center and the JRA-25 reanalysis dataset. The results showed that the number ofTCs forming to the east of 140 °E over the southeastern part of the western North Pacific （WNP） is in highly positive correlation with the variation of the CEF near 125 °E and 150 °E, i.e., the number of tropical cyclogeneses increases when the cross-equatorial flows are strong. Composite analyses showed that during the years of strong CEF, the variations of OLR, vertical wind shear between 200 - 850 hPa, 850 hPa relative vorticity and 200 hPa divergence are favorable for tropical cyclogenesis to the east of 140 °E over the tropical WNP, and vice versa. Moreover, it is also discussed from the view of barotropic energy conversion that during the years of strong CEF, an eastward-extended monsoon trough leads to the rapid growth of eddy kinetic energy over the eastern part ofWNP, which is favorable for tropical cyclogenesis; but during the years of week CEF, the monsoon trough is located westward in the western part of the WNP, consistent with the growth area of eddy kinetic energy. As a result, there are fewer TC geneses over the eastern part of WNP. Besides, the abrupt strengthening of a close-by CEF 2 - 4 days before tropical cyclogenesis may be the one of its triggers.

关 键 词：气候学 热带气旋生成 统计分析 越赤道气流 西北太平洋 正压能量转换 

分 类 号：P444[天文地球—大气科学及气象学]