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华西秋雨演变的新特征及其对大气环流的响应

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华西(21°N-39°N,95°E-114°E)秋雨是中国秋季主要的气候特征之一,长时间连续降水对农作物生产带来不利影响.基于1961-2010年华西地区166个气象站逐日降水资料,综合降水量与降水日数两个因子定义了华西秋雨指数,采用EOF分析、小波分析等方法分析了该指数的演变和时空异常分布特征,以及秋雨异常分布型的大气环流背景.结果表明,华西秋雨有南北两个极大值中心,强度和范围在近50年中存在明显的年代际变化,进入21世纪,其北部秋雨区位置偏北、范围增大及强度增强；主要异常型为秋雨区东北东和西南西之间的反相变化和总体基本一致型;秋季,当东亚副热带西风急流中心西移,中心强风速带偏窄时,华西北部的上升运动加强,同时西太平洋副热带高压偏北、印缅槽偏深及水汽输送偏强偏北,有利于北部水汽辐合,华西秋雨出现北多西南少的异常型；反之亦然.
New Evolution Features of Autumn Rainfall in West China and Its Responses to Atmospheric Circulation
The autumn rainfall in West China (21°N-39°N,95°E-114°E) is one of the main climatic characteristics in the autumn,and the prolonged and continuous rainfall is detrimental to crop production.The daily precipitation data at 166 station in West China during 1961-2010 was used to define IAR(Index of autumn rainfall),which takes the both precipitation and rainy days into consideration.The interdecadal variation and the temporal and spatial distribution characteristics of IAR was analysed with EOF & wavelet method,and the atmospheric circulations was also studied.The results show that:There are maximum IAR centers in both the northern and southern area,with an obvious interdecadal variation in its intensity and range during the last 50 years.The northern part of it gets northward and stronger,and the rangeincreases.The main anomalous type of IAR indicates a ‘northeast-north and west-southwest reversal pattern' anda ‘consisitent pattern on the whole’.When the axis of the climatological subtropical westerly jet gets stronger and migrates westward,the subtropical high migrates westward and northward,and Indian-Myanmar trough gets deeper in the autumn,both the ascending flows and northward vapor transportation strengthens,which contributes to the pattern of more rainfall in the north and less in the southwest part.

Index of autumn rainfallEvolution featureSpatial and temporal distributionsSubtropical westerly jet

罗霄、李栋梁、王慧

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南京信息工程大学 大气科学学院/气象灾害教育部重点实验室,江苏南京 210044

南京大学大气科学学院,江苏南京210093

华西秋雨指数 演变特征 时空分布 副热带西风急流

国家重点基础研究发展规划(973计划)公益性行业(气象)科研专项公益性行业(气象)科研专项2011年度高等学校博士学科点专项科研基金资助课题(博导类)

2013CB430202GYHY201006038GYHY20130602720113228110003

2013

10.7522/j.issn.1000-0534.2013.00018

高原气象
中国科学院寒区旱区环境与工程研究所

高原气象

CSTPCDCSCD北大核心
影响因子：2.193
ISSN：1000-0534
年,卷(期)：2013.32(4)
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