南半球降水对南极海冰涛动异常的响应

运用NCAR/CAM3全球大气环流模式，结合气候学诊断方法，分析了南极海冰涛动异常对南半球降水的影响，并对可能的作用机理进行了初步探讨。结果表明，南半球中纬度降水对海冰涛动异常的响应较为显著，且异常响应的空间分布与海冰涛动类似，分别在南美洲大陆以东大西洋和以西太平洋的广阔海域上存在两个正负值中心。 数值模拟结果显示，海冰涛动异常可以通过改变地表热通量，影响对流层中层大气，进而驱动费莱尔环流的上升支，加强或减弱费莱尔环流的强度，最终对南半球中纬度地区的降水分布产生影响。在阿蒙森/别林斯高晋海外围海冰异常偏少的海域，向上的热通量增加，局地加热会使得费莱尔环流的上升支异常偏强，费莱尔环流的经向输送增强，对应其在中低纬的下沉支也偏强，局地下沉气流异常偏强则会抑制降水的生成，导致降水异常偏少。在威德尔海外围海冰异常偏多的海域，经向环流和降水的响应几乎相反，但因受西南极半岛和南美洲陆面作用的影响，对应经度带费莱尔环流对海冰异常的响应较弱。

RESPONSE OF SOUTHERN HEMISPHERE PRECIPITATION TO ANTARCTIC SEA ICE OSCILLATION ANOMALIES

We analyze the impact of Antarctic sea ice oscillation anomalies on southern hemisphere precipitation pattern with Global atmospheric general circulation model NCAR/CAM3 and climatic diagnosis method, and conduct a preliminary study on the possible mechanism of action. Results show that there was significant response in precipitation to the Antarctic sea ice oscillation anomalies, with positive center over the Atlantic Ocean to the east of South America and negative center over the Pacific Ocean to the west of South America, and its spatial pattern was similar to the Antarctic sea ice oscillation. The results of numerical experiments indicate that sea ice oscillation anomalies can take great effect to the middle troposphere atmosphere by changing the surface heat flux which could drive the ascending branch of Ferrell circulation, strengthen or weaken the intensity of Ferrell circulation, and then make influence on the distribution of southern hemisphere precipitation. In the peripheral waters of Amundsen / Bellingshausen sea where sea ice is less than normal, upward heat flux would increase, which can make the ascending branch of Ferrell circulation abnormally strong. Accordingly, the meridional transport is enhanced and the descending branch is strengthened, this would restrain the formation of precipitation in middle-lower latitude areas. In the peripheral waters of Weddell sea where sea ice is more than normal, the responses of meridional transport and precipitation are almost the opposite. However, the response is much weaker at this longitude zone due to the land surface effect in West Antarctica Peninsula and South America.