中国东部极端降水变化特征及其与大气稳定度的关系  

Variation characteristics of extreme precipitation in eastern China and its relationship with atmospheric stability

作　　者：王苗[1,2] 郭品文[2] 邬昀 

机构地区：[1]武汉区域气候中心,湖北武汉430074 [2]南京信息工程大学气象灾害预报预警与评估协同创新中心,江苏南京210044 [3]湖北省宜昌市气象局,湖北宜昌443000

出　　处：《大气科学学报》2014年第1期47-56,共10页Transactions of Atmospheric Sciences

基　　金：国家科技支撑计划项目(2007BAC29B03);中国气象局气候变化专项(CCSF201205)

摘　　要：利用100°E以东地区通过5%质量控制的392个站逐日降水资料,对近50 a我国东部极端降水变化特征进行分析,并以1948—1976年和1977—2008年为研究子时段,讨论前后两阶段东部地区的大气湿位涡差异及大气稳定度状况。结果表明:我国东部地区极端降水表现出显著的南北差异;北方尤其是华北东部,极端降水量及其所占降水量比例均有下降趋势,而南方尤其是在长江中下游地区二者均呈增加趋势。湿位涡呈"南减北增"的趋势,对流稳定度和斜压稳定度在南方均出现变弱趋势,在北方则增强。大气性质的南北显著变化是我国东部地区极端降水呈"南增北减"分布型的一个重要原因。进一步研究表明,高纬度地区300 hPa层在1976年之后表现为温度负距平场中心,使东部地区高空热力性质产生差异,进而影响了对流稳定度的变化;同时冷中心北侧高层西风分量减小,南侧高层西风风量增大,斜压稳定度相应出现减弱和增强的变化趋势。By using the daily precipitation data of 392 stations over eastern China from 1959 to 2008, which passed 5% quality control, the characteristics of extreme precipitation are studied.The studied time period is divided into 1948-1976 and 1977-2008, and the differences of MPV （moist potential vorticity） and atmospheric stability are discussed during the two periods.Results indicate that the signifi- cant south-north differences of extreme precipitation are found over eastern China. The extreme precipi- tation and its percentage decrease in north of eastern China, especially in east of North China, which in- crease in south of eastern China,especially in the middle and lower reaches of Yangtze River.MPV ex- hibits a reduction in north of eastern China and an increase in south of eastern China.Both the convec- tive stability and the baroclinic stability weaken in the south and strengthen in the north.The siginificant variation of atmospheric property is a main reason of the change trend of the extreme precipitation over eastern China.The further study demonstrates that the temperature anomalies are negative at 300 hPa o- ver the high latitudes after 1976 ,which leads to the difference of thermodynamic properties of upper air in eastern China and affects the convective stability. Meanwhile, the negative temperature anomaliesmake the decrease （increase） of west wind in the north （south） side of the cold center, and the baroclin- ic stability weakens （strengthens） accordingly.

关 键 词：极端降水 大气稳定度 湿位涡 

分 类 号：P426.6[天文地球—大气科学及气象学] P43