西伯利亚高压的年际和年代际异常特征及其对中国冬季气温的影响

Interannual and Interdecadal Anomaly Features of Siberian High and Their Impact on Winter Temperature of China

利用NCEP/NCAR再分析资料和中国160个气象站的气温资料,采用谐波分析、相关分析和奇异值分解等方法,研究了冬季西伯利亚高压(Siberian High,SH)的年际和年代际异常特征及其对中国冬季气温的影响。结果表明:(1)年代际尺度上SH在20世纪60年代末后减弱、收缩、东界西撤、南界北退,21世纪以来SH面积扩张。年际尺度上SH面积的年际方差最大。(2)SH强度、面积和东界经度的年际变率在21世纪以来都增大,SH特征量的年代际变率均在1975年前后由大转小。(3)中国冬季偏冷年的SH较为强大且东扩南伸,同期500 hPa高度类似遥相关欧亚型(EU)正位相的异常分布和增强的欧亚脊对SH发展起主要作用,反之亦然。年际尺度上当SH加强扩张并东扩南伸时,强度的影响最大,中国大部为冷冬,尤其是南方。年代际尺度上面积的影响最强,SH加强扩张(减弱收缩)并东伸(西撤)时,黄河以北气温偏低(高)。(4)年际尺度上当SH强度和面积的变率偏大(小),东界和南界的变率偏小(大)时,中国大部冬季气温的年际波动剧烈(平缓)。年代际尺度上当SH特征量的变率均偏大(小)时,华北和东北冬季气温的年代际波动加大(减小),而南方冬季气温的年代际波动减弱(增大)。

Based on the NCEP/NCAR reanalysis data and air temperature data of the 160 stations in China,by using harmonic analysis,correlation analysis,singular value decomposition and others,the interdecadal and interannual anomaly features of winter Siberian High（SH） and their impact on winter temperature of China are investigated.The results are as followings：（1） On the interdecadal time scale,SH became weak and shrank after the late 1960s,with its east edge retreating to the west and its south edge backing up north.Since the 21st century,the area of SH has a trend of expansion.On the interannual timescale,the area of SH gets the maximum interannual variance.（2） The interannual variability of the intensity and area as well as the east edge of SH have gone up since the beginning of 21st century.On the interdecadal timescale,starting around 1975,the interdecadal variability of the whole SH feature variables all turned smaller than before.（3） SH in colder winter years of China is more powerful,along with the expansion to the east and south,the corresponding anomaly pattern like EU positive phase in the 500 hPa height field and the enhanced Eurasian ridge play a key role in the development of SH,and vice versa.When SH strengthens and enlarges with its frontiers sweeping eastward and southward on interannual timescale,then the intensity of SH makes the most impact,leading to the cold winter in most parts of China,especially in the South,and vice versa.However for the interdecadal scale,the area of SH has the greatest influence on winter temperature.When the SH becomes strong（weak） and expands eastward（retreats westward）,the temperature in the land to the north of the Yellow River turns lower.（4） When there are great（small） variations in the interannual intensity and area of SH,and the interannual variability of its east edge and south edge is at low（high） level,as a result,the interannual fluctuation of temperature in most parts of China is sharp（gentle）.On the interdecadal scale,When all the SH feature variables＇ interdecadal variability increases（declines）,consequently the interdecadal undulation of winter temperature in north and northeast China gets large（small）,while the interdecadal fluctuation of winter temperature in the south is reduced（increased）.