Pacific influences on tropical Atlantic teleconnections to the southern hemisphere high latitudes
Several recent studies have connected Antarctic climate variability to tropical Atlantic sea surface temperatures (SST), proposing a Rossby wave response from the Atlantic as the primary dynamical mechanism. In this investigation, reanalysis data and atmospheric general circulation model experiments...
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ftcdlib:oai:escholarship.org/ark:/13030/qt09w3k1tj 2023-05-15T14:04:02+02:00 Pacific influences on tropical Atlantic teleconnections to the southern hemisphere high latitudes Simpkins, GR Peings, Y Magnusdottir, G 6425 - 6444 2016-01-01 application/pdf https://escholarship.org/uc/item/09w3k1tj unknown eScholarship, University of California qt09w3k1tj https://escholarship.org/uc/item/09w3k1tj public Journal of Climate, vol 29, iss 18 Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering article 2016 ftcdlib 2021-04-16T07:11:37Z Several recent studies have connected Antarctic climate variability to tropical Atlantic sea surface temperatures (SST), proposing a Rossby wave response from the Atlantic as the primary dynamical mechanism. In this investigation, reanalysis data and atmospheric general circulation model experiments are used to further diagnose these dynamical links. Focus is placed on the possible mediating role of Pacific processes, motivated by the similar spatial characteristics of Southern Hemisphere (SH) teleconnections associated with tropical Atlantic and Pacific SST variability. During austral winter (JJA), both reanalyses and model simulations reveal that Atlantic teleconnections represent a two-mechanism process, whereby increased tropical Atlantic SST promotes two conditions: 1) an intensification of the local Atlantic Hadley circulation (HC), driven by enhanced interaction between SST anomalies and the ITCZ, that increases convergence at the descending branch, establishing anomalous vorticity forcing from which a Rossby wave emanates, expressed as a pattern of alternating positive and negative geopotential height anomalies across the SH extratropics (the so-called HC-driven components); and 2) perturbations to the zonal Walker circulation (WC), driven primarily by an SST-induced amplification, that creates a pattern of anomalous upper-level convergence across the central/western Pacific, from which an ENSO-like Rossby wave train can be triggered (the so-called WC-driven components). While the former are found to dominate, the WC-driven components play a subsidiary yet important role. Indeed, it is the superposition of these two separate but interrelated mechanisms that gives the overall observed response. By demonstrating an additional Pacific-related component to Atlantic teleconnections, this study highlights the need to consider Atlantic-Pacific interactions when diagnosing tropical-related climate variability in the SH extratropics. Article in Journal/Newspaper Antarc* Antarctic University of California: eScholarship Antarctic Austral Pacific |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering |
spellingShingle |
Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering Simpkins, GR Peings, Y Magnusdottir, G Pacific influences on tropical Atlantic teleconnections to the southern hemisphere high latitudes |
topic_facet |
Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering |
description |
Several recent studies have connected Antarctic climate variability to tropical Atlantic sea surface temperatures (SST), proposing a Rossby wave response from the Atlantic as the primary dynamical mechanism. In this investigation, reanalysis data and atmospheric general circulation model experiments are used to further diagnose these dynamical links. Focus is placed on the possible mediating role of Pacific processes, motivated by the similar spatial characteristics of Southern Hemisphere (SH) teleconnections associated with tropical Atlantic and Pacific SST variability. During austral winter (JJA), both reanalyses and model simulations reveal that Atlantic teleconnections represent a two-mechanism process, whereby increased tropical Atlantic SST promotes two conditions: 1) an intensification of the local Atlantic Hadley circulation (HC), driven by enhanced interaction between SST anomalies and the ITCZ, that increases convergence at the descending branch, establishing anomalous vorticity forcing from which a Rossby wave emanates, expressed as a pattern of alternating positive and negative geopotential height anomalies across the SH extratropics (the so-called HC-driven components); and 2) perturbations to the zonal Walker circulation (WC), driven primarily by an SST-induced amplification, that creates a pattern of anomalous upper-level convergence across the central/western Pacific, from which an ENSO-like Rossby wave train can be triggered (the so-called WC-driven components). While the former are found to dominate, the WC-driven components play a subsidiary yet important role. Indeed, it is the superposition of these two separate but interrelated mechanisms that gives the overall observed response. By demonstrating an additional Pacific-related component to Atlantic teleconnections, this study highlights the need to consider Atlantic-Pacific interactions when diagnosing tropical-related climate variability in the SH extratropics. |
format |
Article in Journal/Newspaper |
author |
Simpkins, GR Peings, Y Magnusdottir, G |
author_facet |
Simpkins, GR Peings, Y Magnusdottir, G |
author_sort |
Simpkins, GR |
title |
Pacific influences on tropical Atlantic teleconnections to the southern hemisphere high latitudes |
title_short |
Pacific influences on tropical Atlantic teleconnections to the southern hemisphere high latitudes |
title_full |
Pacific influences on tropical Atlantic teleconnections to the southern hemisphere high latitudes |
title_fullStr |
Pacific influences on tropical Atlantic teleconnections to the southern hemisphere high latitudes |
title_full_unstemmed |
Pacific influences on tropical Atlantic teleconnections to the southern hemisphere high latitudes |
title_sort |
pacific influences on tropical atlantic teleconnections to the southern hemisphere high latitudes |
publisher |
eScholarship, University of California |
publishDate |
2016 |
url |
https://escholarship.org/uc/item/09w3k1tj |
op_coverage |
6425 - 6444 |
geographic |
Antarctic Austral Pacific |
geographic_facet |
Antarctic Austral Pacific |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_source |
Journal of Climate, vol 29, iss 18 |
op_relation |
qt09w3k1tj https://escholarship.org/uc/item/09w3k1tj |
op_rights |
public |
_version_ |
1766274972173467648 |