中国东部夏季极端降水事件及大气环流异常分析  

Characteristics of Extreme Precipitation and Associated Anomalous Circulations over Eastern China during Boreal Summer

作　　者：武文博[1,2] 游庆龙 王岱[1] 阮能[1] 

机构地区：[1]南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心,南京210044 [2]河南省气象台,郑州450003

出　　处：《气候与环境研究》2018年第1期47-58,共12页Climatic and Environmental Research

基　　金：国家重点研发计划项目2016YFA0601700;江苏省杰出自然科学基金项目BK20140047;江苏省高校自然科学研究面上项目3KJB170012;江苏高校优势学科建设工程资助项目(PAPD)~~

摘　　要：主要利用1961~2014年中国东部地区438个台站的逐日降水资料和NCEP/NCAR的再分析资料,从大气内部动力角度对夏季不同极端降水情况下的环境场进行分析,结果表明:对长江中下游地区而言,在极端降水频次偏多年时,850 hPa风场及整层水汽输送距平场均表明东亚夏季风偏弱,有利于更多的水汽输送到长江中下游地区,500 hPa鄂霍次克海阻塞高压持续日数偏多,有利于冷空气南下,200 hPa东亚副热带急流偏南,且30°N以南偏西风异常有利于辐散,而在斜压波包从西北东南向传播为极端降水事件分发生集聚了能量;对华北地区极端降水频次偏多年而言,850 hPa风场及整层的水汽输送距平场均表明东亚夏季风偏强,有利于更多的水汽输送到华北地区,500 hPa高度距平场日本海正距平,贝加尔湖蒙古地区为负距平,华北地区东高西低,200 hPa东亚副热带急流偏北,从而导致我国华北地区极端降水频次偏多,能量传播也为西北东南向。这些结果表明极端降水的变化,与大气内部的动力作用和能量的传播有密切的关系。Anomalous circulations associated with various extreme precipitation events in summer are investigated from the perspective of atmosphere dynamics using daily precipitation data collected at 438 stations from 1961 to 2014 in eastern China and the NCEP/NCAR reanalysis data.The results demonstrate that in the middle and lower reaches of the Yangtze River,increases in the frequency of extreme precipitation always correspond to weaker than normal East Asian summer monsoon,which is reflected in abnormal 850-hPa wind field and water vapor flux that are favorable for more water vapor transport to the middle and lower reaches of Yangtze River.At 500 hPa,a blocking high persists over the Okhotsk Sea,which is conductive to the cold air moving southward.The East Asian subtropical westerly jet anomalously moves southward at 200 hPa,while the westerly wind anomalies to the south of 30°N promotes divergence development,and the wave activity fluxes are favorable for generating and maintaining wave perturbations in this region.In North China,corresponding to increases in the frequency of extreme precipitation,anomalies of 850-hPa wind field and water vapor flux indicate that the East Asian summer monsoon is stronger than normal,which strengths the water vapor transport to North China.The positive anomaly is located over the Sea of Japan and the negative anomalies are located over Mongolia,Baikal and their vicinity at 500 hPa.East Asian subtropical westerly jet abnormally shifts northward at 200 hPa,while the wave activity fluxes are also favorable for generating and maintaining wave perturbations in this region.All the above results suggest that the occurrence of extreme summer precipitation in East China is closely associated with atmospheric dynamics and energy transmission.

关 键 词：极端降水事件 环流异常 波作用通量 

分 类 号：P426.6[天文地球—大气科学及气象学]