The Impacts of a Weakened Atlantic Meridional Overturning Circulation on ENSO in a Warmer Climate
The Impacts of a Weakened Atlantic Meridional Overturning Circulation on ENSO in a Warmer Climate
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DOI：
10.1029/2023gl103025
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发表时间：
2023-04
影响因子：
5.2
通讯作者：
Wei Liu;David Duarte Cavalcante Pinto;A. Fedorov;Jiang Zhu
中科院分区：
文献类型：
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作者：
Wei Liu;David Duarte Cavalcante Pinto;A. Fedorov;Jiang Zhu
本文通过比较气候变化模式模拟的大西洋经向翻转环流（AMOC）对厄尔Niño-Southern涛动（ENSO）的影响，量化了人为变暖条件下大西洋经向翻转环流对厄尔Niño-Southern涛动（ENSO）的影响。20世纪80年代以后，AMOC的减弱减弱了赤道东太平洋海温年周期的强度，并在那里诱发了异常的跨赤道北风，使ENSO变率增强了约11%。Bjerknes稳定性指数分析表明，ENSO的增强主要是由于大气风对海温异常的响应增强和海洋风对赤道风应力异常的响应增强而导致的Ekman上升流反馈增强。AMOC减弱也促进了中太平洋El Niño事件的发生，降低了ENSO偏度。然而，这些AMOC对整个21世纪ENSO强度和复杂性的影响小于内部气候变率预期的ENSO变化。
This study quantifies the impacts of the Atlantic Meridional Overturning Circulation (AMOC) on the El Niño–Southern Oscillation (ENSO) under anthropogenic warming by comparing climate change model simulations with declining and fixed strengths of the overturning. After the 1980s, a weakened AMOC is shown to reduce the strength of the annual cycle of sea surface temperature (SST) in the eastern equatorial Pacific and induce anomalous cross‐equatorial northerly winds there, which strengthens ENSO variability by about 11%. An analysis of the Bjerknes stability index reveals that this intensification of ENSO results mainly from enhanced Ekman upwelling feedback due to amplified atmospheric wind response to SST anomalies and oceanic upwelling response to equatorial wind stress anomalies. The weakened AMOC also promotes the occurrence of Central Pacific El Niño events and reduces ENSO skewness. These AMOC impacts on ENSO magnitude and complexity throughout the twenty‐first century are however smaller than ENSO variations expected from internal climate variability.