冬季中国地面气温的变化与前期北半球高层环流异常的联系

INFLUENCE OF UPPER-LEVEL ATMOSPHERIC CIRCULATION ANOMALIES ON WINTER SURFACE TEMPERATURE IN CHINA

利用1960—2009年17层逐日温度场、风场和位势高度场的NCEP/NCAR再分析资料以及中国160站地面气温的观测资料,采用SVD分析、相关分析以及E-P通量计算等方法对冬季中国地面气温的变化与前期平流层异常的联系进行初步的探讨。结果表明,冬季中国平均地面气温与前期2个月北半球高层的温度场、位势高度场以及纬向风场在40°N以北,90°W^180°附近,自平流层上层一直向下延伸到对流层顶附近有一个重要的相关显著区。同时发现,1月中国地面气温异常冷年所对应的北半球中高纬度高层环流异常在前期2个月内为持续性的正(风场为负)异常,而异常暖年所对应的异常随时间变化出现正负(风场为负正)异常的转变,异常自平流层上层向下延伸至对流层内。行星波异常及其传播对平流层-对流层耦合起到了重要的作用,也是造成中国地面气温异常冷(暖)的原因之一。因此,北半球高层环流的异常对中国地面气温的变化有重要的指示意义。

The NCEP/NCAR daily reanalysis of air temperature, horizontal wind and geopotential height from 1 000 to 10 hPa and 160-station observations of the surface temperature from China Meteorological Administration are used to analyze the lag effect of the upper-level atmospheric anomalies on the surface temperature in winter in China. These data cover the period from 1960 to 2009. The results suggest that the anomalies often occur two months ahead north of 40 °N in the Northem Hemisphere from mid- and upper-stratosphere to the upper troposphere. For the cold Januaries, the positive anomalies （negative for the wind） sustain 50-60 days ahead in the stratosphere. But for the warm Januaries, the anomalies change from positive to negative （negative to positive for the wind） almost one month ahead. According to the analysis of E-P flux, the anomaly of the vertical propagation of the planetary wave is one of the major reasons for these anomalies.