摘要
利用NCEP再分析资料和观测的我国160个台站的降水资料,分析了2007年秋季我国北方地区降水异常偏多的时空特征和大尺度环流特征,重点分析了2007年夏秋季开始的La Nia事件对2007年秋季降水和大气环流的影响。结果表明:2007年我国秋季降水出现了典型北多南少的分布,尤其是9月和10月北方地区降水异常偏多。这段时期内,印缅槽偏强,高原东侧的西南季风异常活跃,加强了来自孟加拉湾和南海的水汽向我国北方地区的输送,同时巴尔喀什湖—贝加尔湖高度场偏低,利于不断分裂的冷空气南下,由于西太平洋副热带高压脊线偏北,使冷暖空气主要交汇在我国北方地区。秋季降水EOF第二模态表现为南北反相的分布,与赤道中东太平洋海温异常有密切关系,解释了我国秋季降水10%以上的方差贡献。2007年我国秋季降水和大气环流都表现出了典型La Nia事件影响的特征。
The spatio-temporal characteristics of autumn rainfall anomalies in China in 2007 and the related large-scale atmosphere circulation are analyzed, and effects of the La Nifia event start- ed in August of 2007 are also studied. The autumn rainfall distribution shows a typical feature of more than normal in North China and less than normal in South China, especially in September and October. In these two months, the deep Indian-Burma trough and active southwest monsoon over the east of the Tibetan Plateau strengthened the northward transportation of wet-warm air from the Bay of Bengal and the South China Sea. Meanwhile, the geo-potential height in wide ranges from Balkhash to Baikal is lower than normal, which leads to the cold air taken by the split short waves transporting southward. In addition, the west Pacific subtropical high is more northward than normal, which also supplies the humid southeast air. Under this circulation, the cold airs and warm-wet air were combined constantly over the north China. The second EOF mode of autumn rainfall is similar to the rainfall anomalies in 2007, which explains variance of more 10 % and closely related to the SSTA in the central-eastern Equatorial Pacific. Both autumn rainfall and related circulation anomalies in 2007 present the typical characteristics of La Nina event.
出处
《气象》
CSCD
北大核心
2008年第4期86-94,共9页
Meteorological Monthly
基金
国家科学支撑项目(2006BAC02B04)
中国气象局气象新技术推广项目CMATG2007M04
