夏季东北冷涡持续性活动及其大气环流异常特征的分析
A STUDY OF THE PERSISTENT ACTIVITY OF NORTHEAST COLD VORTEX IN SUMMER AND ITS GENRAL CIRCULATION ANOMALY CHARECTERISTICS
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摘要: 本文首先分析了夏季东北冷涡持续性活动特征及其对东北地区天气气候的影响,然后利用NCEP/NCAR1958～1997年月平均再分析资料,探讨了东北冷涡持续性活动与大气环流异常之间的联系。结果表明,东北冷涡持续性活动是导致东北地区夏季低温的一个十分关键的因子,同时对降水也有重要影响。冷涡活跃年夏季,500hPa高度场会出现以东北地区为中心的南北向和东西向分布的正-负-正距平波列,即与东亚阻高势力偏强而西太平洋副高位置偏南等大尺度环流背景相联系。在对流层中上层,高空西风急流有明显的分支现象,特别是亚洲中纬西风急流位置偏南。而在对流层中下层,东北地区和华北大部以及朝鲜半岛和日本北部等地由明显的气旋式距平环流所控制,并且源自东北及其以西地区的北风距平可一直推进至长江流域并转变为西北风距平,并与那里的西南风距平汇合而形成有利于该地区梅雨偏多时的环流形势,与此同时,长江中下游地区和四川盆地等容易出现垂直速度负距平、涡度正距平和散度负距平分布,而华北和华南大部上述物理量一般为相反的距平分布,从而对应少雨形势,并且中国北方地区(长江以北)对应负温度距平。当夏季东北冷涡活动偏弱时,一般会出现与上述相反的结果。即东北冷涡持续性活动不但对东北地区。Abstract: In this paper,by using the NCEP/NCAR reanalysis monthly mean data from 1958 to 1997 and summer precipit ation and temperature from 69 observation stations of northeast area in China,the persist entactivity of northeast cold vortex and its general circulation anomaly charact eristics have been studied.The results show that the persistent activity of northeast cold vortex is notonly a very important factor to the summer temperature and rainfal of northeast area in China,but also have impact to the precipit ation in some other areas in China,especialy in middle and lower reaches of Yangze River.
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