赤道东太平洋海温异常增暖对低频振荡影响的数值试验

NUMERICAL EXPERIMENT ON THE EFFECT F SEA TEMPERATURE ANOMALIES IN TROPICAL EASTERN PACIFIC TO THE LOW FREQUENCY OSCILLATION

为研究海温的异常增暖对３０－６０天低频振荡的影响，利用ＯＳＵ两层大气环流模式作了两组试验：一组使用气候平均海温，另一组包括两个试验，它们分别设正的海温距平（ΔＳＳＴ）中心位于赤道东太平洋的东部（１００°Ｗ）和中部（１４５°Ｗ）。结果表明：赤道东太平洋冬半年的海温异常增暖可改变低频振荡方差贡献的地理分布，其中当正的ΔＳＳＴ中心位于赤道东太平洋的东部时，热带印度洋和西太平洋地区的低频振荡的方差贡献较为显著，而热带东太平洋的低频振荡较为不活跃；当正的ΔＳＳＴ中心位于赤道东太平洋的中部时，情形则相反，即热带东太平洋的低频振荡的方差贡献较显著，而西太平洋地区的则不活跃。在赤道东太平洋海温异常增暖过程中，低频振荡的传播特性对ΔＳＳＴ中心位置的响应是敏感的，即当正的ΔＳＳＴ中心位置偏于该海区的东部或中部时。

To investigate the effect of SST anomalies on the characters of low frequency oscillation(LFO), two sets of numerical experiment have been performed with the 2 layer OSUGCM. One uses monthly climatic data of SST and the other includs two tests in which the artificial centers of SST anomalies(ΔSST) are assumed in the eastern and the middle of tropical eastern Pacific, respectively. The results of these experiments show that: (1) The SST anomalies in tropical eastern Pacific can modify the distribution of LFO variance. When the positive center of ΔSST is at the middle of tropical eastern Pacific, the value of LFO variance center in tropical eastern Pacific is larger than that in tropical western Pacific and tropical India Ocean. The contrast is true, when the positive center of ΔSST is in the eastem part of tropical eastern Pacific. (2) The response of propagation characters of LFO to the geographic location of ΔSST center is sensitive considerably, that is, the propagation direction and phase velocity of LFO in the two sensitive tests are different considerably.