摘要
西北太平洋副热带高压(简称副高)位置的异常变动对东亚和中国气候有十分重要的影响。为进一步认识副高东西变动对中国西南地区降水的影响,根据东亚—西北太平洋地区高低层大气环流的季节特征,选取700 hPa不同关键区区域平均相对涡度定义了一个新的表征副高位置东西变动的VORT指数。分析发现:该指数不仅能客观定性地表征副高反气旋环流位置的东西变动,而且能反映副高与东亚经向环流变化的关系,副高偏东(西)时,东亚呈负-正-负(正-负-正)经向异常波列。与其他副高指数相比,该指数能较好地反映夏季中国东部雨带位置的季节性移动,并与西南地区降水呈显著相关,对西南地区降水变化有指示意义。其中,6月和7月的相关非常显著,副高偏西时,6月四川西部和南部、云南中北部地区降水偏少,贵州大部降水偏多;7月四川北部和东部、贵州东北部降水偏多,而云南中部和西北部降水偏少,反之亦然。进一步分析还发现,副高与海温的关系与副高活动的位置有关,副高越偏北,与海温的关系就越弱。
The Northwest Pacific subtropical high(abbreviated as subtropical high) is one of the large-scale circulation systems that affect the climate in East Asia. The seasonal north-south movement of the subtropical high has a very important effect on the position of summer rain belt in eastern China. Most of the related researches focus on the movement of the subtropical high in the north-south direction, while less attention is paid to the east-west displacement, especially the influence on the climate in Southwest China.Southwest China is located in the eastward part of the Qinghai-Xizang Plateau, with high altitude and low latitude. Though the influence of the subtropical high on the climate in Southwest China is not as direct as that in the eastern part of China, it is found that the change of subtropical high also plays a very important role by affecting the configuration of atmospheric circulation system. Therefore, it is of great significance to study the anomalous movement of the east-west position of the subtropical high and its influence on the climate in southwestern China in order to understand causes of the climate anomaly.To further understand the influence of the change of the subtropical high, a new index to measure the east-west position of the summer subtropical high is defined by the regionally averaged relative vorticity at700 hPa in different regions based on the climatology circulation. Results show that the index can characterize the east-west displacement of the anticyclonic circulation of the subtropical high more objectively and qualitatively, and it can also reflect the linkage between the subtropical high and meridional circulation over East Asia. When the subtropical high is east(west), there is a negative-positive-negative(positivenegative-positive) meridional anomalous wave train over East Asia. Comparing with other indices, the new index can better reflect the seasonal movement of rain belt position in eastern China in summer and has a significant correlation with precipitation in Southwest China in June and July. When the subtropical high is west, there is less precipitation in western and southern Sichuan, and most in Guizhou in June, and there is more precipitation in northern and eastern Sichuan, northeast Guizhou, and less precipitation in central and northwest Yunnan in July. When the subtropical high is east, the precipitation distribution is almost the contrary. Further analysis also shows that the relationship between the subtropical high and SST is related to the active position of the subtropical high. The farther north the subtropical high is, the weaker the relationship between the subtropical high and the SST is.
作者
晏红明
王灵
Yan Hongming;Wang Ling(Yunnan Climate Center,Kunning 650034;Yunnan Meteorological Bureau,Kunming 650034)
出处
《应用气象学报》
CSCD
北大核心
2019年第3期360-375,共16页
Journal of Applied Meteorological Science
基金
国家自然科学基金项目(41575097)
云南自然科学基金重点项目(2016FA041)
西南区域重点项目(2014-4)
关键词
中国西南地区
夏季降水
西北太平洋副热带高压
东西位置变动
Southwestern China
summer precipitation
Northwestern Pacific subtropical high
east-west position variation
作者简介
晏红明,邮箱:yanhongming2013@163.com.
