摘要
利用1959-2006年西南地区东部20个测站逐日降水量资料和NCEP/NCAR再分析月平均资料以及国家气候中心提供的环流特征量资料,分析了西南地区东部夏季旱涝年的西太平洋副热带高压特征.结果表明:西南地区东部夏季降水(旱涝)及西太平洋副高变化均有明显的年际和年代际变化特征.夏季西太平洋副高面积指数和强度指数之间存在显著的正相关,副高的面积指数、强度指数均与西伸脊点指数呈显著的负相关,当夏季西太平洋副高面积越大强度越强时,西伸就更明显,反之位置偏东.夏季西太平洋副高的脊线位置和北界指数也存在明显的正相关.西南地区东部夏季旱涝与夏季副高南北位置的变化关系非常密切,而与副高面积、强度以及副高的东西位置的相关不显著.一般而言,当副高脊线偏北时,西南地区东部夏季容易出现干旱,反之,则出现洪涝的可能性大.当夏季西太平洋副高脊线位置偏北(偏南)时,有利于出现西南地区东部夏季降水偏少(偏多)的环流形势,并且西南地区东部夏季水汽输送减弱(增强),水汽辐合上升运动也减弱(增强),同时北方冷空气的影响也比较弱(强),因此该地区夏季降水容易偏少(偏多),出现干旱(洪涝)的可能性大.夏季西太平洋副高对西南地区东部夏季旱涝有重要影响,但西南地区东部夏季旱涝还受其他因素的影响,是多种因素的综合作用的结果.
Based on the NCEP/NCAR reanalysis monthly data, the circulation characteristic index values given by the National Climate Center and the daily precipitation data of 20 meteorological observation sta- tions in the eastern part of Southwest China from 1959 to 2006, the features of western Pacific subtropical high （WPSH） associated with drought/flood in summer over the eastern part of Southwest China are ana- lyzed. The results show that WPSH and summer precipitation in Eastern Southwest China are character- ized by an obvious inter-annual and inter-decadal variability. A positive relationship exists between the area and intensity indexes of WPSH in summer, and a significant negative correlation is present between area or intensity index and westward ridge index. And a positive relationship lies between ridge position and north ridge index. The flood-drought over Eastern Southwest China is closely associated with the ridge position of WPSH but not with the other indexes such as area and intensity indexes. Generally speaking, summer drought is more likely to occur in Eastern Southwest China with the ridge position leaning to the north, while summer flood is more liable with the ridge position leaning to the south. It is （not） propitious to ap- pearance of circulation making for summer rainfall in Eastern Southwest China. Furthermore the vapor transport and convergent anabatic velocity strengthening （weakening）, and cold air active （fallow） come from north when the ridge position leans to the south （north）. The summer flood-drought in Eastern Southwest China is significantly influenced by WPSH, and by other {actors as well. In fact, it results from the influence of many factors.
出处
《西南大学学报（自然科学版）》
CAS
CSCD
北大核心
2013年第3期106-116,共11页
Journal of Southwest University(Natural Science Edition)
基金
国家自然科学基金项目(40975058)
公益性行业(气象)科研专项(GYHY201006054)
重庆市自然科学基金计划项目(CSTC2010BB7335)
重庆市自然科学基金计划重点项目(CSTC2008BA0022)
重庆市气象局业务技术攻关项目(ywgg-201303)
重庆市气象局科技计划项目(zl-200810)
关键词
西南地区东部
夏季旱涝
西太平洋副热带高压
特征
Eastern Southwest China
drought/flood in summer
western Pacific subtropical high （WP-SH）
feature
