副热带太平洋海温异常对赤道海洋的影响

利用完全耦合的气候模式进行敏感性试验, 定量研究副热带太平洋不同经度带的海表面温度异常(SSTA)对赤道太平洋的影响。研究发现, 赤道表层和温跃层海温对副热带太平洋(20°?30°N)西部、中部和东部SSTA的热力响应是相当的。 研究中强调大气?海洋耦合在副热带SSTA影响赤道温跃层过程中的决定性作用, 并提出一种间接的、较“海洋通道”机制更为快速的机制: 副热带SSTA引发局地大气的气旋性响应, 继而引起局地海洋内区的上升流和其面向赤道一侧海洋内区的下沉流, 该下沉流造成的局部温跃层暖异常向着赤道传播, 导致赤道温跃层增暖。

Impact of Subtropical Pacific SSTA on the Equatorial Ocean

Using a fully coupled climate model, the impact of subtropical Pacific sea surface temperature anomalies (SSTA) at different longitude bands on the equatorial Pacific is quantitatively studied. Both equatorial SST responses and equatorial thermocline responses to the western, central, and eastern subtropical Pacific (20°?30°N) SSTA are comparable. This work emphasizes the key role of atmosphere-ocean coupling in the subtropical impact on the equatorial thermocline. An indirect mechanism is proposed, which is much faster than the “oceanic tunnel”, in the subtropics-equator coupling, that is, the atmospheric cyclone responding to the subtropical SSTA produces anomalous upwelling in the interior region, while anomalous downwelling occurs in the equatorward flank. The thermocline warming produced by this anomalous downwelling propagates equatorward, and warms the equatorial thermocline.