Mechanisms of Future Changes in Equatorial Upwelling: CMIP5 Intermodel Analysis
Mechanisms of Future Changes in Equatorial Upwelling: CMIP5 Intermodel Analysis
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DOI：
10.1175/jcli-d-19-0128.1
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发表时间：
2020-01-01
影响因子：
4.9
通讯作者：
Deutsch, Curtis
中科院分区：
文献类型：
--
作者：
Terada, Mio;Minobe, Shoshiro;Deutsch, Curtis
利用24个耦合气候模式的资料，研究了1971-2000年和2071-2100年期间赤道上升流的未来变化。多模集合(MME)平均表现出东太平洋赤道上升流的显著减少和西大西洋的弱减少。上升流变化的MME平均值和模式间变化分解为不同的等周期分量和昼夜分量。在太平洋，近海面的昼夜上升流减弱，与减弱的埃克曼抽水有关。赤道潜流(EUC)中心周围75-200m深度的等径上升流由于其流动的密度层变平而减弱。减弱的Ekman泵送和EUC的平坦都是由东太平洋盆地的局地减弱的信风引起的。在赤道大西洋，MME平均值的变化和上升流的模式间变化都与减弱的信风和增强的层结密切相关，尽管这些驱动因素并不是独立的。太平洋的结果表明，未来上升流的减少可能会通过不同的机制在不同的深度产生影响。特别是，东太平洋海盆海温的快速升温可能主要是由近地表昼夜上升流减少引起的，而不是与EUC平坦相关的等日上升流减少引起的，这在更深的层面上是重要的。
The future change in equatorial upwelling between 1971-2000 and 2071-2100 is investigated using data from 24 coupled climate models. The multimodel ensemble (MME) mean exhibits substantial equatorial upwelling decrease in the eastern Pacific and weaker decrease in the western Atlantic Ocean. The MME mean of upwelling change and intermodel variation of that are decomposed into distinct isopycnal and diapycnal components. In the Pacific, the diapycnal upwelling decreases near the surface, associated with a weakened Ekman pumping. The isopycnal upwelling decreases at depths of 75-200 m around the core of the Equatorial Undercurrent (EUC) due to flattening of the density layer in which it flows. Both the weakened Ekman pumping and the EUC flattening are induced by the locally weakened trade wind over the eastern Pacific basin. In the equatorial Atlantic, both the change in MME mean and the intermodel variation of upwellings are significantly related to the weakened trade wind and enhanced stratification, although these drivers are not independent. The results for the Pacific Ocean imply that future reduction in upwelling may have impacts at different depths by different mechanisms. In particular, the rapid warming of sea surface temperature in the eastern Pacific basin may be mainly caused by the near-surface diapycnal upwelling reduction rather than isopycnal upwelling reduction associated EUC flattening, which is important at deeper levels.