巴伦支海海冰异常对初夏大气环流和东亚天气影响的数值研究

NUMERICAL STUDY ON THE INFLUENCE OF THE ANOMALYOF SEA ICE IN BARENTS SEA ON THE GENERALCIRCULATION AND THE WEATHER IN EASTASIA DURING THE EARLY SUMMER

本文利用在ＮＣＡＲ气候模式ＣＣＭ１（Ｒ１５Ｌ１２）基础上改变为用于长期数值预报的ＣＣＭ１（Ｒ１５Ｌ７），以１９９１年５月２日１２时（ＧＭＴ）国家气象中心客观分析资料为初始场，分别以巴伦支海附近海域不同的海冰边界作为下垫面极冰条件，进行了相应的月长期数值预报试验。以研究该海区海冰对大气环流特别是东亚天气的影响。试验＜Ａ＞以接近于９１年５月平均冰边界作为极冰边界条件，试验＜Ｂ＞和试验＜Ｃ＞分别对应于海冰异常偏多和异常偏少两种情况。试验结果显示控制试验＜Ａ＞的预报与实况有较好的相关，表明ＣＣＭＩ（Ｒ１５Ｌ７）模式具有较可信的月预报能力。试验结果还表明，试验海区海冰异常主要存在两个波列影响到中低纬度。对东亚初夏天气也有着不可忽视的重要作用，影响着经由巴尔喀什湖和贝加尔湖之间通道南下的冷空气活动的强度。海冰偏多时，东亚冷空气活动增多．范围较大；反之，海冰偏少时，冷空气较弱且活动位置较北，使得冷暖气流交绥区位于黄河流域及以北，雨带随之北移。因此在研究初夏东亚环流和天气异常时，海冰也应作为一个重要的因子加以考虑。

To investigate the influence of various sea ice boundaries in Barents Sea on the general circulation and the weather in east Asia during the early summer, three experiments for themonthly numerical weather prediction were performed by emloying the CCMI (R15L7) Modelwhich was formed from NCAR' S CCM1 (R15L12) Model by making some changes for beingmore Suitable to the long-range numerical weather prediction, and the objective analysis data of2 May 1991 were used as initial field. Three runs are corresponding to three different ice boundaries in Barents Sea which are as follows: (1) an approximate monthly mean ice boundary ofMay in 1991, (2) the maximum extent of ice, (3) the minimum extent of ice.The resuts of experiments show that the anomaly of ice boundary in the Barents Sea affectsthe intensity of the acitivities of the cold air which moves through the channel between theI-ake Bajkal and the Lake Balkhash. When the ice boundary is at its minimum extent in BarentsSea, the activities of the cold air weaken and accompany with a northward withdraw and theinterface of the cold air and the warm-damp flow will occur over the basin of the Yellow Riveror more northward of it. On the contrary, when the ice boundary extends to its maximum extent, the intensity of the activities of the cold air strengthens and its influence reaches to thesouth of china.