摘要
2009年秋季云南出现了大范围降水极端偏少现象,导致秋季全省库塘蓄水严重不足,成为后期云南出现秋、冬、春和初夏连旱的主要原因之一.因此,通过相关分析和平均值显著性检验方法分析了此次云南秋季降水极端偏少的异常气候特征.结果表明:造成2009年秋季云南大范围降水极端偏少的最主要原因是亚洲极涡显著偏弱,持续偏强偏西的西太平洋副热带高压阻挡了东亚冷空气的向南入侵,使得冷空气明显偏北偏东.而孟加拉湾地区对流层中低层的异常反气旋环流使得赤道索马里附近由南向北的越赤道气流异常偏西偏北,且阻挡了西南气流向云南输送水汽.可见,干燥的对流层大气以及较弱的垂直上升运动是云南区域内高低层大气表现最异常的特征.相关分析还发现,云南秋季降水与南半球极地及中高纬高度场都存在显著的相关关系,与赤道西太平洋地区的对流活动具有显著正相关,且2009年在显著相关区域内高度场和赤道西太平洋对流都表现出不利于云南秋季降水偏多的显著异常气候特征.
A extremely less rain event occurs over Yunnan during autumn in 2009.It leads to seriously insufficient of reservoir impoundments in autumn of 2009 and it is one of the main reasons of continuous drought in Yunnan from autumn to early summer of next year.Therefore,by using the method of correlation and significant test of average value,we analysis the abnormal climate features caused extremely less rain in autumn.Firstly,The results show that the extremely less rain is associated with the significant weaker Asia Polar Vortex and the abnormal Subtropical High.In autumn of 2009,the Subtropical High is so stronger and more westward that the North cold air is obstructed and is more northward and eastward.Secondly.the results show that the abnormal anticyclone in high and low level of Bengal gulf causes the airflow near Somalia to be more northward and westward and holds up the water vapor of Yunnan transported by southwest monsoon.The airflow near Somalia gets over equator from southern hemisphere to northern hemisphere.It is thus clear that the dry atmosphere and the weaker vertical motion in troposphere is the most anormal atmosphere features in autumn of 2009.The correlation analysis also found that there is significant correlativity between precipitation of Yunnan in fall and height field of polar region and high-latitude and low-latitude region.The positive correlativity between precipitation of Yunnan in fall and OLR of Equatorial Pacific Ocean is significant and pass the test of 0.05.In autumn of 2009,the significant correlation regions of high and OLR of Equatorial Pacific Ocean show that the precipitation of Yunnan is extremely less.
出处
《云南大学学报（自然科学版）》
CAS
CSCD
北大核心
2011年第3期317-324,共8页
Journal of Yunnan University(Natural Sciences Edition)
基金
云南省社会发展科技计划资助(2009CA023)
云南省气象局业务能力建设重点项目资助(YZ200904)
国家自然科学基金面上项目资助(41075072)
关键词
云南秋季
降水极端偏少
干旱
大气环流
显著异常
Yunnan autumn
extremely less rain
drought
atmospheric circulation
significant abnormity
