大气环流对冬季黑潮延伸体海温异常的响应

Response of atmospheric circulation to SST anomalies of kuroshio extension in winter

利用全球大气环流模式CAM3,研究了冬季北半球大气环流和东亚副热带西风急流对同期黑潮延伸体海温异常增暖响应的敏感性及东亚西风急流的响应机理。结果表明,模式能较好地刻画冬季黑潮延伸体海温异常增暖导致的北半球大气环流异常,特别是中纬地区大气环流异常"+、-"相间的分布特征。中高纬是大气对冬季黑潮延伸体海温异常响应的敏感区,随着海温异常幅度的增大,北半球整体的环流异常形势不变,仅异常的强度和范围略有不同。对于东亚副热带西风急流,模式能较好地再现其分布和冬季黑潮延伸体海温异常增暖导致西风急流减弱的变化特征。机理分析表明,东北太平洋上气旋式异常环流和黑潮延伸区及欧亚大陆东南部反气旋式异常环流的存在和35°N南北温度梯度的减小,是导致冬季黑潮延伸体海温异常增暖后东亚西风急流减弱的重要原因。

The response of the Northern Hemisphere atmospheric circulation and the East Asia subtropical westerly jet to the sea surface temperature（SST） anomalies of the Kuroshio Extension in winter was investigated as well as the response mechanism of westerly jet by simulation tests using community atmosphere model 3（CAM3）.The results show that the model can well depict the atmospheric circulation anomalies caused by the warmer SST in the Kuroshio Extension,especially the distribution characteristics with positive and negative values in alternation in the mid-latitude zone.Moreover,the middle and high latitude zones are the sensitive areas of the response of the atmosphere to the SST anomalies of the Kuroshio Extension in winter.With the increase of the SST anomalies,the basic distribution of the atmospheric circulation anomalies is invariable,only the discrepancy of intensity and range of the anomalies is different.For subtropical westerly jet,the variety caused by the warmer SST of the Kuroshio Extension in winter can be well reproduced by the model.The analysis of the mechanism shows that the existence of the cyclonic anomaly circulation in northeast Pacific ocean and the anticyclonic anomaly circulations in the Kuroshio Extension and southeast Eurasia and the decrease of the meridional temperature gradient around 35 °N are the important reasons for the weaken of westerly jet caused by the SST anomaly of the Kuroshio Extension.