异常弱的南极涛动和2006年我国春季沙尘气候形势

从2005/2006年冬季南极涛动的变异出发,讨论2006年我国春季沙尘气候形势,进而考察南极涛动对我国沙尘气候的预测能力。2005/2006年冬季南极涛动非常弱,在两半球间的经向遥相关的作用下,出现南半球中高纬西风减弱,欧亚西风减弱,欧亚冷空气活跃,西伯利亚、蒙古国、我国北方大部地区(包括华北)2005年冬季12月气温较多年平均偏低,这样就造成沙源地区的冻土层增厚,春季回暖后,沙尘物质条件丰富。因此,在弱南极涛动的影响下,春季蒙古气旋活跃,地面大风增加,我国华北地区春季沙尘天气频繁发生。

The Weakening of the Antarctic Oscillation and the Dust Climate during Spring 2006 in China

Based on the variation of Antarctic Oscillation(AAO),the dust climate during spring in China in 2006 was discussed.The use of the signal of AAO in the forecast of dust climate in China is also examined.The results show that the AAO has been very weak since last winter in 2005/2006.The weaker AAO(DJF)is concurrent with weaker westerlies in Southern Hemisphere and weaker westeries in Eurasia,resulting in the colder temperature in Asia via the meridional teleconnection from the Antarctica to the Northern Hemisphere.The surface temperatures in December of 2005 are lower than the normal in the Siberia area,Mongolia area as well as north China,resulting in deeper frozen land surface in winter and more sandy sources in spring.Therefore,there is more Mongolia cyclongenesis and strong winds under the weaker AAO,resulting in more dust days during spring.