大气环流异常对云南8月低温的影响

Influence of anomalous general circulation on low temperature of Yunnan in August

应用1951-2005年NCEP/NCAR月平均再分析资料与云南8月气温资料进行相关分析,发现在云南8月低温年,位势高度场的显著相关区在欧亚大陆地区具有"-+-"的波列结构,显著相关区在副热带地区表现也较好;据此讨论了云南8月低温发生时的大气环流特征,得出200hPa南亚高压偏弱,500hPa欧亚大陆西风槽脊异常发展,副高偏弱是导致云南8月低温的主要原因。

The correlation analysis is made by using the monthly averaged reanalysis data from NCEP/NCAR and the suface air temperature data of Yunnan in August between 1951 and 2005. The relation between the low temperature of Yunnan in August and the features of the general circulation in all levels in North Hemisphere is also discussed. The results show that there is an notable correlation regions in Eurasia with - ＋ - wave pattern and the significant correlation lies in the subtropical region. South Asia high is weak at 200hPa. The abnormal development of the trough and ridge in westerlies and the weak subtropical high at 500hPa are the key factors of the low temperature of Yunnan in August.