Acta Geographica Sinica ›› 2010, Vol. 65 ›› Issue (11): 1325-1335.doi: 10.11821/xb201011002

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The Spatio-temporal Variation of Winter Climate Anomalies in Southwestern China and the Possible Influencing Factors

JIANG Xingwen1,2, LI Yueqing1   

  1. 1. Institute of Plateau Meteorology, China Meteorological Administration, Chengdu 610072, China;

    2. College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
  • Received:2010-06-15 Revised:2010-08-06 Online:2010-11-20 Published:2010-11-20
  • Supported by:

    National Natural Science Foundation of China, No.40875060; No.60832012; Basic Research and Operation Program of Institute of Plateau Meteorology, China Meteorological Administration, No.BROP201017]

Abstract:

The impacts of winter extreme climate events in recent years on socio-economy indicated that the importance of winter climate anomalies is the same as its summer counterpart in southwestern China (SWC). The spatio-temporal variations and its possible causes of climate anomalies in SWC were investigated by utilizing observation data from 1961 to 2010. The results indicate that surface air temperature anomalies in SWC have two dominant modes, one is homogenous, the other is dipole in latitudinal direction. The former was caused by the anomalies of East Asian winter monsoon, the latter arose from the anomalies of both subtropical west Pacific high and regional cold air in lower troposphere. The most dominant mode of precipitation anomalies in SWC is homogenous and it has a high correlation with northern hemisphere annular mode (NAM, AO). NAM and ENSO did not have significant impacts on the variation of surface air temperature in SWC. The anomalies of NAM would lead to the anomalies of tropical circulations. When NAM is in positive (negative) phase, the winter precipitation is more (less) than normal in SWC. Precipitation in the whole SWC increased during El Niño winter, but increased in central SWC, and decreased in west and east of SWC during La Niña winter. The severe drought in SWC in the winter of 2010 is more likely caused by anomalies of NAM instead of El Niño.

Key words: southwestern China, the winter of 2010, drought, winter monsoon, northern hemisphere annular mode (NAM, AO)