Unprecedented reduction and quick recovery of the South Indian Ocean heat content and sea level in 2014–2018
Unprecedented reduction and quick recovery of the South Indian Ocean heat content and sea level in 2014–2018
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DOI：
10.1126/sciadv.abc1151
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发表时间：
2020-09
期刊：
影响因子：
13.6
通讯作者：
D. Volkov;Sang‐Ki Lee;A. Gordon;M. Rudko
中科院分区：
文献类型：
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作者：
D. Volkov;Sang‐Ki Lee;A. Gordon;M. Rudko
遥强迫和局地强迫导致南印度洋热含量出现前所未有的下降和快速恢复。在2014 - 2016年强厄尔尼诺现象开始之后，2004 - 2013年亚热带南印度洋（SIO）全盆地范围的海平面和热含量长达十年的增长以一次前所未有的下降而告终，在2017 - 2018年弱拉尼娜现象期间又迅速恢复。在此，我们表明2014 - 2016年厄尔尼诺现象通过一种不寻常的组合导致了观测到的降温，即来自太平洋的热平流减少（在南印度洋东部占主导）以及导致等温线变浅的全盆地范围的气旋性风异常（在南印度洋西部占主导）。随后的恢复主要是由与更强信风相关的反气旋性风异常所驱动，这导致了等温线加深和上层海洋变暖，有效地抑制了从东部边界传播的2014 - 2016年冷却信号。这里呈现的结果凸显了由遥强迫和局地强迫驱动的南印度洋热含量变化的复杂性。
Remote and local forcing led to unprecedented drop and quick recovery in the South Indian Ocean heat content. Following the onset of the strong 2014–2016 El Niño, a decade-long increase of the basin-wide sea level and heat content in the subtropical southern Indian Ocean (SIO) in 2004–2013 ended with an unprecedented drop, which quickly recovered during the weak 2017–2018 La Niña. Here, we show that the 2014–2016 El Niño contributed to the observed cooling through an unusual combination of both the reduced heat advection from the Pacific (dominant in the eastern SIO) and the basin-wide cyclonic wind anomaly that led to shoaling of isotherms (dominant in the western SIO). The ensuing recovery was mainly forced by an anticyclonic wind anomaly associated with stronger trade winds that caused deepening of isotherms and upper-ocean warming, effectively suppressing the 2014–2016 cooling signal propagating from the eastern boundary. The results presented here highlight the complexity of the SIO heat content variability driven by remote and local forcing.