中国东南部冬季降水变化及其环流特征

Precipitation variation over southeastern China in winter and its circulation pattern

利用1951—2011年中国160站降水资料及NCEP/NCAR再分析资料,分析了中国东南部冬季降水的年际变化及与之相关的环流和水汽输送特征。结果表明:中国东南部冬季降水年际差异较明显,当降水异常偏多(少)时,蒙古高压及中国广大南方地区海平面气压异常偏低(高),而亚洲附近的洋面上则异常偏高(低);500hPa上,巴尔喀什湖附近的高压脊和东亚大槽均偏弱(强);高层东亚西风急流异常偏弱(强),中东地区急流异常偏强(弱);中国东部20～30°N出现显著异常上升(下沉)运动,低纬度地区出现异常下沉(上升)运动。影响中国东南部冬季降水的水汽输送主要有两支:来自西风带绕高原的南支气流,经过阿拉伯海和孟加拉湾向华南的输送水汽;来自低纬西太平洋,经南海向中国西南的水汽输送。此外,东亚冬季风与中国东南部冬季降水关系密切。

Based on the precipitation data at 160 stations in China and the NCEP/NCAR reanalysis data during 1951--2011, this paper studies the interannual variability of winter precipitation over southeastern China and associated circulation and water vapor transport characteristics. Results show that interannual variation of winter precipitation over southeastern China is significant. When the precipitation anomaly is positive （negative）, the sea level pressure anomalies are negative （positive） of Mongolian high and over southern China, and positive（negative） in the adjacent sea area of Asia;At 500 hPa, the high pressure ridge near the Balkhash Lake and East Asia trough both are weaker（stronger） ;westerly jet of Eastern Asia is weaker（ stronger）, and westerly jet of the Middle East is stronger（weaker）. There is a significant abnormal ascending（sinking） motion over 20-30°N eastern China and an abnormal sinking（ascending） motion in low latitudes. Two dominating water vapor transports affect winter precipitation over southeastern China. Firstly, a water vapor transport comes from the south branch airflow of the westerlies around the Tibetan Plateau, by Arabian Sea and the Bay of Bengal, to South China. Secondly, a water vapor transport comes from the low-latitude western Pacific. by South China Sea, to Southwest China. In addition, there is a negative correlation between East Asian winter monsoon index and winter precipitation over southeastern China.