青藏高原-孟加拉湾大气热力差异与夏季暴雨  

Possible Effects of the Difference in Atmospheric Heating Between the Tibetan Plateau and the Bay of Bengal on Spatiotemporal Evolution of Rainstorms

作　　者：陈金秋 施晓晖[1] Chen Jinqiu;Shi Xiaohui(State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,Beijing 100081)

机构地区：[1]中国气象科学研究院灾害天气国家重点实验室,北京100081

出　　处：《应用气象学报》2022年第2期244-256,共13页Journal of Applied Meteorological Science

基　　金：国家自然科学基金面上项目(41775060);中国气象科学研究院基本科研业务费重点项目(2021Z004)。

摘　　要：利用1979—2019年多年平均5—8月的逐日气象资料,采用EOF,MV-EOF、相关分析和合成分析等方法,对夏季青藏高原-孟加拉湾的大气热源与中国东部暴雨的时空演变特征及两者之间的联系进行探讨。研究结果表明:MV-EOF能够很好地表现不同要素的空间分布特征及其时间演变之间的联系。结果显示:在气候平均状态下,强降水事件分别发生在华南地区、华西和长江中下游地区时,青藏高原东部和孟加拉湾的大气加热出现相反的变化趋势,说明青藏高原东部和孟加拉湾之间的海陆热力对比很可能是导致中国东部强降水事件在不同地点发生的关键因素之一。合成分析结果揭示可能物理机制:青藏高原和孟加拉湾的热力对比变化通过调制大气垂直环流,影响南亚高压和西北太平洋副热带高压的位置和强度,改变水汽输送,最终对中国东部暴雨事件的时空变化产生重要的影响。Based on the climatical daily meteorological data from May to August during 1979-2019,using the methods of empirical orthogonal function(EOF) and multivariate empirical orthogonal function(MVEOF),correlation analysis and synthetic analysis,the characteristics of the temporal and spatial evolution of atmospheric heat sources around the Tibetan Plateau(TP) and the Bay of Bengal(BOB) are investigated,and their relationships with the rainstorm in eastern China are analyzed.It’s found that MV-EOF can well show the relationship between the spatial distribution characteristics of different elements and their temporal evolution.The results reflect the close relationship between the thermal condition of TP and its surrounding areas,the summer monsoon circulation,and the rainstorm in eastern China.Correspondingly,the rainstorm events occur in Southeast China and the middle and lower reaches of the Yangtze River,respectively.The spatial variation characteristics of the atmospheric heating in TP and surrounding areas show significant differences in the second and the third modes of MV-EOF,especially in the reversal of the thermal contrast between TP and BOB.The atmospheric heating in TP and BOB shows an opposite trend,which indicates that the sea-land thermal comparison between TP and BOB is likely to be one of the key factors leading to the occurrence of rainstorm events in different places in eastern China.The results of the synthetic analysis suggest a possible physical mechanism:When the atmospheric heating is weak over TP and strong over BOB,there is a strong ascending motion over BOB and its surrounding areas,which is conducive to the maintaining of South Asian high(SAH) and the northwestern Pacific subtropical high(WPSH) in southward position,and also conducive to the occurrence of cyclonic water vapor transportation circulation in Southeast China-South China Sea-Northwest Pacific.It weakens the southwesterly water vapor transportation,thus induces the continuous heavy precipitation in South China.After the increasi

关 键 词：青藏高原 孟加拉湾 大气热力差异 暴雨 时空演变 

分 类 号：P426.62[天文地球—大气科学及气象学]