Pivotal Role of Mixed‐Layer Depth in Tropical Atlantic Multidecadal Variability
Abstract The tropical arm of Atlantic Multidecadal Variability (AMV) influences climate worldwide, yet the mechanisms generating it remain unclear. Here, we examine experiments with sea surface temperature (SST)‐restoring in the extratropical North Atlantic in multiple models and use mixed‐layer hea...
Published in: | Geophysical Research Letters |
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Online Access: | https://doi.org/10.1029/2024GL110057 https://doaj.org/article/468ccd18437a4fd381b9a0aa66db2d04 |
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ftdoajarticles:oai:doaj.org/article:468ccd18437a4fd381b9a0aa66db2d04 2024-09-09T19:55:51+00:00 Pivotal Role of Mixed‐Layer Depth in Tropical Atlantic Multidecadal Variability Balaji Senapati Christopher H. O’Reilly Jon Robson 2024-08-01T00:00:00Z https://doi.org/10.1029/2024GL110057 https://doaj.org/article/468ccd18437a4fd381b9a0aa66db2d04 EN eng Wiley https://doi.org/10.1029/2024GL110057 https://doaj.org/toc/0094-8276 https://doaj.org/toc/1944-8007 1944-8007 0094-8276 doi:10.1029/2024GL110057 https://doaj.org/article/468ccd18437a4fd381b9a0aa66db2d04 Geophysical Research Letters, Vol 51, Iss 15, Pp n/a-n/a (2024) North Atlantic ocean‐atmosphere coupling Atlantic Multidecadal Variability tropical variability Geophysics. Cosmic physics QC801-809 article 2024 ftdoajarticles https://doi.org/10.1029/2024GL110057 2024-08-19T14:56:40Z Abstract The tropical arm of Atlantic Multidecadal Variability (AMV) influences climate worldwide, yet the mechanisms generating it remain unclear. Here, we examine experiments with sea surface temperature (SST)‐restoring in the extratropical North Atlantic in multiple models and use mixed‐layer heat budgets to elucidate the important mechanisms. Our results demonstrate that the tropical AMV is driven by wind‐mixed‐layer‐SST feedback. The evolution has two phases with tropical AMV SST anomalies growing from April to October and decaying from November to March. The amplitude of the growth phase surpasses that of the decay phase, resulting in overall tropical Atlantic warming during positive AMV phases. During summer, positive SST anomalies in the extratropics weaken the trade winds, resulting in a shallower mixed‐layer with reduced heat capacity. Subsequent absorption of climatological shortwave radiation in this shallower mixed‐layer then causes SSTs to warm, generating the tropical AMV. Importantly, anomalous surface heat‐fluxes make modest contributions to tropical AMV in these experiments. Article in Journal/Newspaper North Atlantic Directory of Open Access Journals: DOAJ Articles Geophysical Research Letters 51 15 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
North Atlantic ocean‐atmosphere coupling Atlantic Multidecadal Variability tropical variability Geophysics. Cosmic physics QC801-809 |
spellingShingle |
North Atlantic ocean‐atmosphere coupling Atlantic Multidecadal Variability tropical variability Geophysics. Cosmic physics QC801-809 Balaji Senapati Christopher H. O’Reilly Jon Robson Pivotal Role of Mixed‐Layer Depth in Tropical Atlantic Multidecadal Variability |
topic_facet |
North Atlantic ocean‐atmosphere coupling Atlantic Multidecadal Variability tropical variability Geophysics. Cosmic physics QC801-809 |
description |
Abstract The tropical arm of Atlantic Multidecadal Variability (AMV) influences climate worldwide, yet the mechanisms generating it remain unclear. Here, we examine experiments with sea surface temperature (SST)‐restoring in the extratropical North Atlantic in multiple models and use mixed‐layer heat budgets to elucidate the important mechanisms. Our results demonstrate that the tropical AMV is driven by wind‐mixed‐layer‐SST feedback. The evolution has two phases with tropical AMV SST anomalies growing from April to October and decaying from November to March. The amplitude of the growth phase surpasses that of the decay phase, resulting in overall tropical Atlantic warming during positive AMV phases. During summer, positive SST anomalies in the extratropics weaken the trade winds, resulting in a shallower mixed‐layer with reduced heat capacity. Subsequent absorption of climatological shortwave radiation in this shallower mixed‐layer then causes SSTs to warm, generating the tropical AMV. Importantly, anomalous surface heat‐fluxes make modest contributions to tropical AMV in these experiments. |
format |
Article in Journal/Newspaper |
author |
Balaji Senapati Christopher H. O’Reilly Jon Robson |
author_facet |
Balaji Senapati Christopher H. O’Reilly Jon Robson |
author_sort |
Balaji Senapati |
title |
Pivotal Role of Mixed‐Layer Depth in Tropical Atlantic Multidecadal Variability |
title_short |
Pivotal Role of Mixed‐Layer Depth in Tropical Atlantic Multidecadal Variability |
title_full |
Pivotal Role of Mixed‐Layer Depth in Tropical Atlantic Multidecadal Variability |
title_fullStr |
Pivotal Role of Mixed‐Layer Depth in Tropical Atlantic Multidecadal Variability |
title_full_unstemmed |
Pivotal Role of Mixed‐Layer Depth in Tropical Atlantic Multidecadal Variability |
title_sort |
pivotal role of mixed‐layer depth in tropical atlantic multidecadal variability |
publisher |
Wiley |
publishDate |
2024 |
url |
https://doi.org/10.1029/2024GL110057 https://doaj.org/article/468ccd18437a4fd381b9a0aa66db2d04 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Geophysical Research Letters, Vol 51, Iss 15, Pp n/a-n/a (2024) |
op_relation |
https://doi.org/10.1029/2024GL110057 https://doaj.org/toc/0094-8276 https://doaj.org/toc/1944-8007 1944-8007 0094-8276 doi:10.1029/2024GL110057 https://doaj.org/article/468ccd18437a4fd381b9a0aa66db2d04 |
op_doi |
https://doi.org/10.1029/2024GL110057 |
container_title |
Geophysical Research Letters |
container_volume |
51 |
container_issue |
15 |
_version_ |
1809926115865657344 |