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Eddy‐induced carbon transport across the Antarctic Circumpolar Current
Author(s) -
Moreau Sébastien,
Penna Alice Della,
Llort Joan,
Patel Ramkrushnbhai,
Langlais Clothilde,
Boyd Philip W.,
Matear Richard J.,
Phillips Helen E.,
Trull Thomas W.,
Tilbrook Bronte,
Lenton Andrew,
Strutton Peter G.
Publication year - 2017
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1002/2017gb005669
Subject(s) - eddy , oceanography , geology , carbon cycle , antarctic intermediate water , total inorganic carbon , aragonite , mesoscale meteorology , calcite , atmospheric sciences , environmental science , carbon dioxide , thermohaline circulation , chemistry , mineralogy , meteorology , ecology , north atlantic deep water , physics , organic chemistry , ecosystem , turbulence , biology
Abstract The implications of a mesoscale eddy for relevant properties of the Southern Ocean carbon cycle are examined with in situ observations. We explored carbon properties inside a large (~190 km diameter) cyclonic eddy that detached from the Subantarctic Front (SAF) south of Tasmania in March 2016. Based on remote sensing, the eddy was present for ~2 months in the Subantarctic Zone (SAZ), an important region of oceanic carbon dioxide (CO 2 ) uptake throughout the annual cycle and carbon subduction (i.e., where mode and intermediate waters form), before it was reabsorbed into the SAF. The eddy was sampled during the middle of its life, 1 month after it spawned. Comparatively, the eddy was ~3°C colder, 0.5 practical salinity unit fresher, and less biologically productive than surrounding SAZ waters. The eddy was also richer in dissolved inorganic carbon (DIC) and had lower saturation states of aragonite and calcite than the surrounding SAZ waters. As a consequence, it was a strong source of CO 2 to the atmosphere (with fluxes up to +25 mmol C m −2 d −1 ). Compared to the SAF waters, from which it originated, DIC concentration in the eddy was ~20 μmol kg −1 lower, indicating lateral mixing, small‐scale recirculation, or eddy stirring with lower‐DIC SAZ waters by the time the eddy was observed. As they are commonly spawned from the Antarctic Circumpolar Current, and as 50% of them decay in the SAZ (the rest being reabsorbed by the SAF‐N), these types of eddies may represent a significant south‐north transport pathway for carbon across the ACC and may alter the carbon properties of SAZ waters.