Effects of the Tibetan Plateau Winter Monsoon and SST in Tropical Pacific Ocean on the Winter Temperature in Southwest China

Using NCEP/NCAR R2 reanalysis daily data and the daily temperature data at 115 meteorological stations in southwest China from 1979 to 2008,the variation characteristics of the Tibetan Plateau winter monsoon(TPWM) and its relation with winter temperature in southwest China are analyzed and discussed by the correlation and composite analysis. The main conclusions are as follows: There exists obvious negative correlation between the TPWM and the winter temperature in southwest China. There exist significant differences in the distribution of the circulation fields in the high,middle and low layer of troposphere when the TPWM is in the strong and weak phase. In the strong TPWM phase,because the East Asian winter monsoon is weak with high Nino3.4 sea surface temperature,the circulation fields in troposphere do not lead to the lower temperature in southwest China. On the contrary,in the weak TPWM phase,the East Asian winter monsoon is strong with low sea surface temperature in Nino3.4,thus the circulation fields in troposphere make great contributions to the lower temperature in southwest China.