摘要
本文对2012年我国夏季降水的实况和预测进行简要回顾,发现2012年夏季降水大体呈北方涝、长江旱的分布,主雨带位于黄河流域及其以北,降水异常偏多的区域主要位于西北大部、内蒙古和环渤海湾,黄淮与江淮地区降水偏少,江汉至淮河上游一带干旱严重;预测的主雨带位于华北南部至淮河,较实况偏南。对我国北方降水异常偏多的成因分析表明:2012年夏季欧亚中高纬地区阻塞高压(简称阻高)强盛,同时东北冷涡活动频繁,中高纬500 hPa高度场从西至东呈"+-+"的分布,这种环流形势没有造成长江洪涝是因为东亚夏季风异常偏强,同时西太平洋副热带高压(副高)偏北,冷暖空气对峙于我国北方地区,导致北方降水异常偏多。分析还表明阻高、东北冷涡、东亚夏季风和副高这四个系统的不同配置影响着冷暖气流的对峙位置,进而形成我国夏季的主雨带。最后通过定量和定性判断相结合的方法,选取了2012年夏季降水的最佳相似年和最佳相反年,对比分析了2012年夏季降水与其最佳相似年和最佳相反年的海温演变与东亚夏季风环流系统主要成员的差异:1959年夏季降水作为2012年夏季降水的最佳相似年,虽然海温及东亚夏季风系统关键成员异常不明显,但是和2012年也呈近似相反的特征;而1980年夏季降水作为2012年夏季降水的最佳相反年,海温及东亚夏季风环流系统关键成员和2012年呈显著的反向特征,这些观测事实反映了我国夏季降水与海温及东亚夏季风环流系统关键成员这些主要影响因子之间关系的年代际变化。
The observed and predicted 2012 precipitation in China is reviewed. The distribution of the observed summer precipitation shows flooding in northern China and drought in the Yangtze River basin. The main rain band is located in the Yellow River basin and north of that region. Areas of abnormally positive precipitation anomalies are mainly located in northwestern China, Mongolia, and the area around Bohai Gulf, whereas areas of negative precipitation anomalies are located in the Huaihe River and Yangtze River basin, esneciallv the .lianoh^n tn I4n^ih~ r^oi^n Th,~ ma~ A;~~~A ~;~band is located in the region from southern North China to the Huaihe River, which is to the south of the observed rain band. Further analysis of the reason behind the extremely heavy northern summer precipitation shows that the blocking high was strong over mid-high latitudes in Eurasia in the summer of 2012, whereas the Northeast China cold vortex was frequent and the 500 hPa geopotential height field over the mid-high latitudes showed the pattern of＂＋ -- ＋＂ from west to east. However, there is no correlation of floods in the Yangtze River basin and atmospheric circulation. The floods are primarily attributed to the abnormally strong East Asia summer monsoon, whereas the western Pacific subtropical high （WPSH） moves northward causing the cold and warm air to meet, which leads to positive precipitation anomalies in the north. Furthermore, the analysis suggests that the position of the main rain belt in the summer depends on the location of the interaction between cold and warm air, which is influenced by the different configurations of the blocking high over Eurasia at mid-high latitudes, the northeast cold vortex, the East Asia summer monsoon, and the WPSH. Finally, by combining quantitative calculations with qualitative judgment, the most similar and most opposite year to the summer precipitation of 2012 were selected and the three-year differences for the SST and the main members of the summer monsoon circulation system of East Asia were analyzed. In 1959, which a year most similar to 2012, the SST and key elements of the East Asia summer monsoon system do not show obvious abnormal signals, whereas it shows approximately opposite features compared to 2012. In 1980, which a year much different than 2012, the features of SST and key elements of the East Asia summer monsoon system are opposite compared to 2012. These features reflect the decadal variations in the summer rainfall in China and the main factors affecting it; that is, the SST and the East Asia summer monsoon system.
出处
《大气科学》
CSCD
北大核心
2014年第2期237-250,共14页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金项目40930952
41105055
国家重点基础研究发展计划项目2012CB955902
2013CB430204
公益性行业科研专项GYHY201106016
关键词
夏季降水
东亚夏季风环流系统
天气模型
年代际变化
Summer precipitation, East Asia summer monsoon system, Weather pattern, Decadal variations
