中国大范围持续性低温事件与中国南方降水异常  

Wintertime Extensive and Persistent Low-Temperature Events of China and Anomalous Precipitation over Southern China

作　　者：符仙月 布和朝鲁[2,3] 

机构地区：[1]浙江省义乌市气象局,义乌322000 [2]中国科学院大气物理研究所国际气候与环境科学中心,北京100029 [3]中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室,北京100029

出　　处：《大气科学》2013年第6期1247-1260,共14页Chinese Journal of Atmospheric Sciences

基　　金：国家科技支撑计划2009BAC51B02;国家国际科技合作专项项目2011DFG23450

摘　　要：本文利用1951~2009年的数据资料,探讨了与冬季大范围持续性低温事件对应的中国南方降水多寡的原因以及不同降水类型事件的不同前兆信号。主要结果如下:(1)欧亚大陆中高纬大型斜脊斜槽是中国大范围持续性低温事件的关键环流特征。降水偏多型和偏少型低温事件的中高纬环流系统存在显著差异:当大型斜脊的纬向尺度较大且其正高度距平中心偏强时,斜槽的负距平中心靠近东亚大槽区,西伯利亚高压大范围加强,南侵冷空气活动偏强,使中国南方地区降水偏少。相反,当大型斜脊的纬向尺度相对小时,斜槽位置偏西,西伯利亚高压加强范围偏小,南侵冷空气活动也偏弱,有利于中国南方地区降水偏多。(2)在低温事件中我国南方地区的降水多寡,也取决于西太副高和孟加拉湾南支槽。当西太副高和孟加拉湾南支槽加强时,来自西太平洋、南海和孟加拉湾的三支暖湿气流到达我国南方地区,导致南方降水偏多,反之亦然。(3)不同降水类型低温事件的前兆环流信号(之前1~3侯)显著不同。降水偏多型低温事件前期,源自北大西洋地区的波列向东亚地区传播。降水偏少型事件前期,极涡在欧亚大陆一侧的次极区显著减弱,同时极涡呈两极型,一极伸向南欧及地中海地区,另一极伸向阿留申群岛。在中期—延伸期时间尺度上,这一结果可为持续性低温事件降水形势的预测提供依据。The possible causes of anomalous precipitation over southern China during the wintertime extensive and persistent low-temperature events(EPLTEs) are analyzed using long-term(1951–2009) reanalysis and observational data.The precursory circulation signals for the two types of EPLTEs with below-normal and above-normal precipitation levels over southern China are also investigated. The mid-tropospheric tilted ridge and trough with a continental scale was observed to be the key common circulation feature among the EPLTEs. The high and mid-latitude circulation features associated with the two types of EPLTEs differ significantly. When the large-scale tilted ridge shows a larger zonal extent and its positive height anomaly center attains stronger amplitude, the tilted trough appears to be close to the climatological axis of the East Asian major trough. In this case, the Siberian High is amplified extensively and the southward cold air activity is strengthened, causing below-normal precipitation over southern China. By contrast, when the large-scale tilted ridge shows a smaller zonal extent, the tilted trough is located inland, away from the climatological axis of the East Asian major trough. In this circumstance, the extent of the amplified Siberian High is smaller, the southward cold air activity is moderate, and the EPLTE is accompanied by above-normal precipitation over southern China. Moreover, it was discovered that the precipitation anomalies over southern China during EPLTEs are determined by the roles of the western Pacific subtropical high and the southern branch trough over the Bay of Bangladesh, which when intensified causes warm and wet water vapor to be transported from the western Pacific Ocean, South China Sea,and the Bay of Bangladesh to southern China to create abundant precipitation over southern China and vise versa. Further,with respect to the two types of EPLTEs, the precursory signals of the atmospheric circulation occurring 1–3 pentads before the occurrence of EPLTE, also differ. Prior to the

关 键 词：持续性低温事件 降水异常 大型斜脊斜槽 西太平洋副热带高压 前兆信号 

分 类 号：P423[天文地球—大气科学及气象学] P426.6