南极威德尔海区域海冰异常对初夏东亚大气环流和天气影响的数值研究

Numerical study on influence of anomaly of sea ice in the Weddell Sea on seasonal transition in East Asia during early summer

利用经过改变用于长期数值预报的CCM1（R15L7）模式以1975年1月16日00Z模式适应场为初始场积分5个月，研究南极威德尔海附近（60°W～30°E）海冰的面积异常对东亚初夏环流转换季节的影响．发现当南极海冰偏多时，在亚洲北部冷空气活动在初夏仍然很多，势力还很强，东亚南北两支急流分支仍很明显，各种环流特征更偏向于冬季型，不利于东亚初夏的环流季节转换．海冰异常偏少时则相反，亚洲北部的冷空气活动明显减弱，南方暖气流势力明显加强北移，东亚的两支急流也趋于合并北抬，环流形势更接近于夏季型，海冰的减少促进了东亚初夏的环流季节转换过程．

By employing the CCM1 (R15L7) model which was formed from NCAR'S CCM1 (R15L12) model by making somechanges for being more suitable to the long-range numerical weather prediction, three numerical experiments-the climatic monthly mean ice boundary in the Weddell Sea (60°～ 30°E), the maximum extent and the minimum extent of that-have ben carriedout to investigate the influence of ice boundary in Antarctica on the seasonal transition in the early summer in East Asia. The results show that when sea ice boundary is at its maximum extent, the characteristics of circulation in East Asia are more like thatin winter, the divergence of north and south westerly jet stream in East Asia is clear, and the activities of cold air in North Asiaare still active and their intensity is still strong. More ice in the Wedded Sea has no benefit to the seasonal transition in East Asia When sea ice is at its minimum extent, on the contrary, the activities of cold air in North Asia are weakened, the warm-dampflow in South Asia becomes strong and moves more northward and the trend of confluence of two westerly hi stream-the northern one and the southern one-is more clear in East Asia, and the characteristics of circulation are favourable to advance the seasonal transition in East Asia. (In the basis of model results, we conclude that ice rnatgin anomalies in the Wedded alga are capableof influencing the circulation and climate in East Asia. The anomalies of ice boundary wiU hinder or advance the seasonal transitionin East Asia during the early summer.