1949—2009年欧亚大陆强冷空气活动频次的变化特征

利用NCEP/NCAR提供的1949—2009年sig995层逐日平均温度资料,分析了近60 a欧亚大陆强冷空气活动频次年际变化的地区差异,并讨论了强冷空气活动的区域特征以及各区域强冷空气活动的变化特征。结果表明:欧亚大陆强冷空气活动可分为34个变化区,按照年代际变化及地理位置相邻可进一步归纳为9类地区。9类地区的强冷空气活动年频次存在共同变化特征,例如在20世纪60年代末至80年代中期普遍偏少;但也存在差异,例如80年代中期至90年代初高纬度地区偏多,而较低纬度的中国以及周边地区偏少。值得注意的是,新地岛周边地区以及西伯利亚中、南部地区强冷空气活动频次始于20世纪90年代中期的下降趋势延续至今,近几年欧亚大陆多数地区强冷空气活动频次偏少。

VARIATION CHARACTERISTICS OF STRONG COLD AIR ACTIVITY FREQUENCY IN EURASIA FROM 1949 TO 2009

Based on the NCEP/NCAR daily average temperature data（1949—2009） of sig995 layer,the regional differences of interannual variation of the strong cold air activity（SCAA） in Eurasia are analyzed.The regional characteristics and the interannual and interdecadal changes of SCAA in each sub-region are discussed.Results show that Eurasia SCAA can be divided into 34 areas,which can be classified into 9 categories in accordance with the interdecadal change and location adjacence.The frequency of SCAA in 9 categories areas have common variation characteristics,for example,from the late 1960s to the mid-1980s it was generally less than normal.There were also some differences,for example,with high（low） frequency in high latitude areas（low latitude areas such as China and surroundings） from the mid-1980s to the early 1990s.In addition,the downtrend of SCAA frequency in Novaya Zemlya and the central and southern Siberia continues from mid-1990s to 2009.In recent years,SCAA frequency is less than normal in most parts of Eurasia.