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Decadal‐Scale Increases of Anthropogenic CO 2 in Antarctic Bottom Water in the Indian and Western Pacific Sectors of the Southern Ocean
Author(s) -
Murata Akihiko,
Kumamoto Yuichiro,
Sasaki Kenichi
Publication year - 2019
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl080604
Subject(s) - antarctic bottom water , transect , oceanography , bottom water , sink (geography) , environmental science , water column , surface water , geology , geography , cartography , environmental engineering
We determined decadal‐scale increases of anthropogenic CO 2 in the water column using data sets collected 17 years apart (1994–1996 and 2012–2013) along a transect at nominal 62°S in the Indian and western Pacific sectors of the Southern Ocean. Large increases of anthropogenic CO 2 (up to 9.1 ± 1.5 μmol/kg), closely following atmospheric CO 2 increases, were found in Antarctic Bottom Water (AABW), previously considered a small sink of anthropogenic CO 2 . Vertical distributions of anthropogenic CO 2 increases showed significant positive correlations with those of changes in CFC‐12 and SF 6 , implying that the distributions were mainly controlled by physical processes such as ventilation and circulation. Calculated uptake rates of anthropogenic CO 2 by AABW were between 0.29 and 0.39 mol·m −2 ·yr −1 in five longitudinal segments of the transect. In accounting for the large increase of anthropogenic CO 2 in AABW, sea surface conditions in the formation region of AABW are important.