东南沿海盛夏气温异常的海气特征分析

Analysis of Oceanic and Atmospheric Features for Anomalous Air Temperature in Midsummer in the China's Southeastern Coastal Regions

利用1951—2006年共56年东南沿海地区宁波、温州、福州、永安和汕头5站盛夏(7—8月)气温资料和北半球500 hPa高度及北太平洋海温资料,分析了东南沿海地区盛夏气温异常的年代际变化,并对其形成进行海气特征分析。发现东南沿海地区盛夏气温变化,上世纪50年代至80年代为偏低时期,其中1970年代为显著偏低时期,异常低温年频繁出现;1990年代至今为偏高时期,其中进入本世纪后为显著偏高时期,异常高温年频繁发生。异常高、低温年的形成与北半球大气环流和北太平洋海温的异常变化相联系。前期冬、春季节北半球副高强度、北非副高强度和西太平洋副高强度及西伸脊点异常变化,对东南沿海盛夏气温具有很好的指示性。前期冬季12月和1月份的北太平洋海温距平分布型,对东南沿海盛夏气温的异常变化也具有很好的指示意义。

The decadal variation of anomalous air temperature in midsummer in the southeastern coastal regions of China is analyzed and its causes are discussed with the oceanic and atmospheric features respectively by using the data of air temperature observed from Ningbo,Wenzhou,Fuzhou,Yong an and Shantou Stations in midsummer (July-August),500 hPa geopotential height in the Northern Hemisphere as well as sea surface temperature (SST) in the northern Pacific from 1951 to 2006.It found that the period of low temperature in midsummer is dominant from 1950s to 1980s,with the significantly low temperature in 1970s,and the years of anomalous low temperature appear frequently in 1970s.The air temperature is higher since 1990s,with significantly high temperature after the year of 2000,the years of anomalous high temperature occur frequently.The occurrence of anomalous high and low temperatures is associated with the anomalous changes of the atmospheric circulation in the Northern Hemisphere and SST in northern Pacific.The anomalous changes of subtropical high intensities in the Northern Hemisphere,in northern Africa and in western Pacific and westward ridge locations of subtropical high in the precedent winter and spring exhibit an effectual indicator for air temperature in midsummer in southeastern coastal regions. Additionally,the distribution patterns of SST anomaly over the northern Pacific in the precedent December and present January are also closely related to the anomalous changes of air temperature in midsummer in southeastern coastal regions.