Antarctic Bottom Water Warming, Freshening, and Contraction in the Eastern Bellingshausen Basin

Abstract Antarctic Bottom Water has been warming in recent decades throughout most of the oceans and freshening in regions close to its Indian and Pacific sector sources. We assess warming rates on isobars in the eastern Pacific sector of the Southern Ocean using CTD data collected from shipboard su...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Gregory C. Johnson, A. K. M. Sadman Mahmud, Alison M. Macdonald, Benjamin S. Twining
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 2024
Subjects:
Antarctic Bottom Water
Deep Argo
Bellingshausen Basin
Geophysics. Cosmic physics
QC801-809
Antarc*
Antarctic
Southern Ocean
Online Access:https://doi.org/10.1029/2024GL109937
https://doaj.org/article/cf968357817848fe94debbfe0e9f725e
Description
Summary:Abstract Antarctic Bottom Water has been warming in recent decades throughout most of the oceans and freshening in regions close to its Indian and Pacific sector sources. We assess warming rates on isobars in the eastern Pacific sector of the Southern Ocean using CTD data collected from shipboard surveys from the early 1990s through the late 2010s together with CTD data collected from Deep Argo floats deployed in the region in January 2023. We show cooling and freshening in the temperature‐salinity relation for water colder than ∼0.4°C. We further find a recent acceleration in the regional bottom water warming rate vertically averaged for pressures exceeding 3,700 dbar, with the 2017/18 to 2023/24 trend of 7.5 (±0.9) m°C yr−1 nearly triple the 1992/95 to 2023/24 trend of 2.8 (±0.2) m°C yr−1. The 0.2°C isotherm descent rate for these same time periods nearly quadruples from 7.8 to 28 m yr−1.

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