西南地区冬季旱涝特征及其与北极涛动关系  

Spatial and temporal characteristics of winter drought/flood in southwest China and correlation with Arctic Oscillation

作　　者：孔祥伟[1] 于乐江[2] 刘新伟[1] 

机构地区：[1]兰州中心气象台,甘肃兰州730020 [2]南京信息工程大学,江苏南京210044

出　　处：《干旱区地理》2012年第6期875-882,共8页Arid Land Geography

基　　金：中国气象局预报员专项项目"高分辨率数值模式产品在暴雨预报中的应用(CMAYBY2012-065)"资助

摘　　要：利用1951-2010年我国西南地区内32站月平均降水资料及NCEP/NCAR再分析资料,对西南地区冬季旱涝时空分布特征及其与北极涛动(AO)的关系进行了研究分析。结果表明:近60 a西南地区冬季降水量和旱涝事件平均发生频次均呈东南向西北递减分布,其中滇、黔、桂交界处和四川南部为降水偏多事件多发区,而渝、滇西南、黔东部及四川盆地是干旱事件多发区,特旱事件的发生概率也较高,并有逐年增加的趋势;冬季旱涝以周期为12 a、8 a左右的低频振荡最为显著,近几年均处于负位相;冬季AO与西南地区同期降水呈显著的正相关,AO异常偏强(弱)时,则西南地区降水异常偏多(少)。Based on monthly rainfall data of 32 stations in southwest China from National Climate Center and the National Center for Environmental Prediction/National Center for Atmospheric Research（NCEP/NCAR） reanalysis monthly data from 1951 to 2010, the spatial and temporal characteristics of wintertime rainfall anomalies in south- west China, and the relationships between those and the Arctic Oscillation （AO） are investigated using precipitation Z indices, Molet wavelet analysis, and Singular value decomposition （SVD）. Precipitation Z indices method is used to determine grades of drought and more-rainfall events according to wintertime rainfall. The main results show that in the southeast of southwest China, the wintertime rainfall and frequency of more-rainfall events and drought e- vents are larger than those in the northwest, more than half of the recent 60 years are anomalous rainfall years, drought events are less than the more-rainfall events. The more-rainfall events are apt to occur in southern Sichuan, Yunnan, Guizhou and Guangxi. However, Chongqing, southwestern Yunnan, eastern Guizhou and Sichuan Basin is easy to be influenced by drought events, the probability of occurrence of extreme drought is also higher, and the extreme weather is becoming more and more frequent. Z indices in winter show interannual and interdecadal varia- bility with significant 12 yr and 8 yr periods. In recent years Z indices are at negative phase with less wintertime rainfall and more frequent drought events. There is a strong relationship between AO and the wintertime rainfall in southwest China. when the AO is stronger（weaker） , anomalous cyclone （anticyclone） occurs over the Bay of Ben- gal, and the southwest China is controlled by anomalous warm wet（ cold dry） flow from the southwest（northwest） and the water vapor is more（less）. Meanwhile the East Asia winter monsoon is weaker （stronger） and more west- wards （eastwards） than usual, there is ascending （descending） movement at the level o

关 键 词：西南地区 冬季 旱涝 北极涛动(AO) 

分 类 号：P461[天文地球—大气科学及气象学]