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The Ocean and Atmosphere in the Maritime Continent and Their Impacts
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South-Atlantic-forced multidecadal teleconnection to the mid-latitude South Indian Ocean
P-P5-08-S
Jiaqing Xue* , Institute of Atmospheric Physics, Chinese Academy of Sciences
Cheng Sun, College of Earth Science, University of Chinese Academy of Sciences
Jianping Li, College of Earth Science, University of Chinese Academy of Sciences
Jiangyu Mao, Institute of Atmospheric Physics, Chinese Academy of Sciences
Presenter Email: 1506425793@qq.com |
| Sea surface temperature (SST) in the mid-latitude South Indian Ocean (MSIO) exhibits prominent multidecadal fluctuations that have profound climate impacts for regions around the Indian Ocean. Observational analysis suggests these multidecadal fluctuations can be explained by remote forcing from South Atlantic multidecadal variability (SAMV). A suite of Atlantic Pacemaker experiments performs well in reproducing the observed MSIO SST multidecadal variation and its association with the South Atlantic. This trans-basin covariability can be described by an atmospheric bridge mechanism, in which SAMV-related SST warming weakens regional meridional circulation over the South Atlantic, suppressing convection over tropical Africa. The reduced diabatic heating then drives cold atmospheric Kelvin wave that penetrates into the tropical Indian Ocean, leading to an anomalous cyclonic circulation there that weakens the westerlies over the MSIO and subsequently triggers the warming of MSIO. This initial warming is further amplified by local SST-water vapor positive feedback over the MSIO. |
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