欧亚冬季温带反气旋活动的气候特征

Climatology of the winter extratropical antiyclones over Eurasia

中文关键词:  反气旋  生成  消亡  强度  斜压性  距离  持续时间

英文关键词:Anticyclones  Genesis  Lysis  Intensity  Baroclinity  Distance  Life-span

中文摘要:

      利用NCEP/NCAR再分析数据，通过判定和追踪温带反气旋的客观方法统计分析了1948-2013年欧亚地区冬季温带反气旋的生成、消亡、移动、生命史、强度等气候特征。结果表明，反气旋的主要源地位于蒙古高原、伊朗及其周边地区、地中海沿岸、中西伯利亚、波罗的海西北部、俄罗斯东北部等地，其中，蒙古高原和伊朗等地也是强反气旋最主要的源地。反气旋活动的大值分布区和反气旋生成的大值中心分布十分相似，主要活跃区对应低空平均经向温度梯度大值区和高空脊前。除源于蒙古高原和西伯利亚东北部的强、弱反气旋的移动距离差别不明显外，其他地区的反气旋移动距离与强度有密切关系。持续1-2 d的反气旋占总数的44.2%，而只有3.2%的反气旋生命史超过一周，且强反气旋比弱反气旋更易持续较长时间。

英文摘要:

      This study presents the climatology of anticyclones in Eurasia during the winter based on the sea level pressure and 10 m winds extracted from the NCEP/NCAR reanalysis data for the period of 1948-2013. Results show that the main sources of anticyclones are:The Mongolian Plateau,Iran and its neighboring regions, the Mediterranean coast, central Siberia, north and west of the Baltic Sea and northeastern Russia. The Mongolian Plateau and Iran regions are the main sources of strong anticyclone events. Areas of large frequency of anticyclone occurrence also correspond to centers of high anticyclogenesis. Major areas of active anticyclones correspond to areas of large meridional gradients of temperature in the lower troposphere (850 hPa) and in the front of the upper-level ridge. There is a close relationship between the intensity and displacement of the anticyclones except for those originating from Mongolian Plateau and northeastern Russia. 44.2% of the total anticyclone events last 1-2 d, and only 3.2% last for more than 7 d. Strong anticyclone events are more likely to last longer than the weak ones.