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Changes in the Atlantic Sector of the Southern Ocean estimated from the CESM Last Millennium Ensemble

Published online by Cambridge University Press:  18 January 2019

Ilana Wainer Open the ORCID record for Ilana Wainer [Opens in a new window]  and
Peter R. Gent
Ilana Wainer*
Affiliation:
Oceanography Institute at the University of São Paulo, São Paulo-SP, 05508-120, Brazil
Peter R. Gent
Affiliation:
National Center for Atmospheric Research, Boulder, CO80307, USA
*
*[email protected]
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Abstract

The changes in the Antarctic Circumpolar Current system associated with the Polar, sub-Antarctic and Subtropical Fronts in the Atlantic are examined in a ten-member ensemble using the Community Earth System Model. Results for the ensemble average mean show that the Polar Front at 25°W shifts to the south by 0.8° during 1970–2000 compared to its mean latitude over the period 1050–1950. This shift is significant because it is more than twice the standard deviation of the mean latitude time series during 1050–1950. The shift is caused by a slight southward displacement of the Antarctic Circumpolar Current, which in turn is caused by a southward shift in the latitude of the maximum zonal wind stress. The sub-Antarctic Front also shows a small southward shift after 1970, with a maximum latitudinal displacement of 0.2°. However, this shift is not significant compared to the standard deviation of the time series during 1050–1950. The Subtropical Front does not change its latitude during 1970–2000 compared to 1050–2000 because there is very little change in the wind-stress curl in the subtropics. Differences in temperature and salinity throughout the water column at 25°W reveal that during 1970–2000 there is freshening of Antarctic Intermediate Water, whereas the Circumpolar Deep Water becomes saltier.

Keywords

ACC systemclimate changeSouth AtlanticSouthern Hemispherewesterlies
Type
Physical Sciences
Information
Antarctic Science , Volume 31 , Issue 1 , February 2019 , pp. 37 - 51
Copyright
© Antarctic Science Ltd 2019 

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