Middepth decadal warming and freshening in the South Atlantic

TitleMiddepth decadal warming and freshening in the South Atlantic
Publication TypeJournal Article
Year of Publication2017
AuthorsGiglio D., Johnson G.C
JournalJournal of Geophysical Research-Oceans
Volume122
Pagination973-979
Date Published2017/02
Type of ArticleArticle
ISBN Number2169-9275
Accession NumberWOS:000398063100012
Keywordsargo array; circulation; deep-water; global ocean; heat; intermediate; section; trends
Abstract

South Atlantic Ocean middepth water property (temperature, salinity, oxygen, nutrients, etc.) distributions are set by salty, well-ventilated, and relatively nutrient-poor North Atlantic Deep Water (NADW) spreading southward toward the Southern Ocean underneath fresher, well-ventilated, and relatively nutrient-poor northward spreading Antarctic Intermediate Water (AAIW). The layer between the NADW and AAIW is oxygen-poor and nutrient-rich, with small vertical temperature gradients. Salinity stratification dominates the vertical density gradient, hence the layer is referred to as Salinity Stratified Layer (SSL). Decadal warming (0.044 degrees C decade(-1)) and freshening (0.006 g kg(-1) decade(-1)) of this layer are analyzed using Argo data, a climatology, and repeat hydrographic sections. Warming within the SSL accumulates heat at a rate of similar to 20 TW, is unlikely to be caused by vertical heave, and is consistent with anomalous southward advection of order 10(2) km decade(-1) in the Atlantic Meridional Overturning Circulation. Salinity changes within the SSL are consistent with a downward velocity anomaly of order 10 m decade(-1).

DOI10.1002/2016jc012246
Short TitleJ Geophys Res-Oceans
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