Tropical connections to climatic change in the extratropical Southern Hemisphere: The role of atlantic SST trends

The austral spring relationships between sea surface temperature (SST) trends and the Southern Hemisphere (SH) extratropical atmospheric circulation are investigated using an atmospheric general circulation model (AGCM). A suite of simulations are analyzed wherein the AGCM is forced by underlying SS...

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Bibliographic Details
Published in:Journal of Climate
Main Authors: Simpkins, GR, McGregor, S, Taschetto, AS, Ciasto, LM, England, MH
Format: Article in Journal/Newspaper
Language:unknown
Published: American Meteorological Society 2014
Subjects:
13 Climate Action
anzsrc-for: 0401 Atmospheric Sciences
anzsrc-for: 0405 Oceanography
anzsrc-for: 0909 Geomatic Engineering
Antarc*
Antarctic
Antarctic Peninsula
Antarctica
West Antarctica
Online Access:http://hdl.handle.net/1959.4/unsworks_13557
https://doi.org/10.1175/jcli-d-13-00615.1
Description
Summary:The austral spring relationships between sea surface temperature (SST) trends and the Southern Hemisphere (SH) extratropical atmospheric circulation are investigated using an atmospheric general circulation model (AGCM). A suite of simulations are analyzed wherein the AGCM is forced by underlying SST conditions in which recent trends are constrained to individual ocean basins (Pacific, Indian, and Atlantic), allowing the impact of each region to be assessed in isolation. When forced with observed global SST, the model broadly replicates the spatial pattern of extratropical SHgeopotential height trends seen in reanalyses. However, when forcing by each ocean basin separately, similar structures arise only when Atlantic SST trends are included. It is further shown that teleconnections from the Atlantic are associated with perturbations to the zonal Walker circulation and the corresponding intensification of the local Hadley cell, the impact of which results in the development of atmospheric Rossby waves. Thus, increased Rossby waves, forced by positive Atlantic SST trends, may have played a role in driving geopotential height trends in the SH extratropics. Furthermore, these atmospheric circulation changes promote warming throughout the Antarctic Peninsula and much of West Antarctica, with a pattern that closely matches recent observational records. This suggests that Atlantic SST trends, via a teleconnection to the SH extratropics, may have contributed to springtime climatic change in the SH extratropics over the past three decades. © 2014 American Meteorological Society.

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