摘要
利用NCEP/NCAR提供的1961～2008年500 hPa位势高度值和风场月平均再分析资料、国家气候中心提供的西太平洋副高指数资料和陕西夏季降水资料,探讨了前期大气环流异常对陕西夏季旱涝的影响及机制。结果表明,陕西夏季旱涝与前期秋季、冬季、春季的低纬和中高纬西风带大气环流异常密切相关,旱涝年对应不同的前期大气环流特征,当前期高度场上从太平洋到北美呈"+-+"的距平波列结构,即正的PNA大气遥相关分布时,夏季西太平洋副高增强、偏西,中高纬度巴尔喀什湖和鄂霍次克海阻塞高压也随之加强,陕西中南部有异常西南风水汽输送,北部有北风异常,陕西夏季易涝,反之易旱。副高脊线位置主要影响陕西夏季雨带的南北移动。前期太平洋海温通过影响西太平洋副高强度、位置变化影响陕西夏季降水,当前期秋、冬赤道中东太平洋海温偏高,海温呈ElNin珘o型分布时,夏季副高偏强、偏西,陕西夏季降水偏多。
Based on NCEP/NCAR monthly global reanalysis data from 1961 to 2008,west Pacific subtropical high index information from National Climate Center and summer precipitation data of Shaanxi,the influence of preceding atmospheric circulation anomalies on summer rainfall in Shaanxi and its mechanism were discussed.Results showed that there were close relationship between droughts（floods） in summer of Shaanxi and westerly belt circulation anomalies at low and high latitude in the preceding autumn,winter and spring.When positive PNA atmospheric teleconnection distribution was appeared in preceding atmospheric circulation,the western Pacific subtropical high would strengthen and extend westward in summer,and the Balkhash Lake and Okhotsk Sea block high would also be stronger,which resulted in abnormal southwest wind transporting water vapour over the central and southern Shaanxi,and abnormal north wind bringing cold air over the northern Shaanxi,there would be flooding in summer of Shaanxi,whereas,it would be drought.The location of the subtropical high ridge mainly affected the move of rainfall belt in north and south direction in summer of Shaanxi.When SST in the middle east equatorial Pacific was higher,western Pacific subtropical high was stronger and moved westward in the coming summer,then there would be more rain in summer of Shaanxi.
出处
《干旱气象》
2012年第4期546-554,共9页
Journal of Arid Meteorology
基金
国家自然科学基金(41075072)
陕西省气象局预报员专项(2012Y-30)共同资助
关键词
陕西夏季旱涝
前期大气环流异常
西太平洋副高指数
太平洋—北美遥相关(PNA)
droughts/floods in summer of Shaanxi
the preceding atmospheric circulation anomalies
western Pacific subtropical high index
Pacific-north America teleconnection（PNA）
