Variability of nutrients and carbon dioxide in the Antarctic Intermediate Water between 1990 and 2014

Antarctic Intermediate Water (AAIW) formation constitutes an important mechanism for the export of macronutrients out of the Southern Ocean that fuels primary production in low latitudes. We used quality-controlled gridded data from five hydrographic cruises between 1990 and 2014 to examine decadal...

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Bibliographic Details
Published in:Ocean Dynamics
Main Authors: Panassa, Essowe, Santana-Casiano, J. Magdalena, González-Dávila, Melchor, Hoppema, Mario, van Heuven, Steven M.A.C., Völker, Christoph, Wolf-Gladrow, Dieter, Hauck, Judith
Other Authors: 57200601507, 6701344294, 6603931257, 35401714600, 23977259000, 7004309320, 6701350155, 36127520000, 17795518, 579253, 518149, 563803, 1478102, 5706370, 845775, 1900432, WOS:Panassa, E, WOS:Santana-Casiano, JM, WOS:Gonzalez-Davila, M, WOS:Hoppema, M, WOS:van Heuven, SMAC, WOS:Volker, C, WOS:Wolf-Gladrow, D, WOS:Hauck, J
Format: Article in Journal/Newspaper
Language:English
Published: 2018
Subjects:
251002 Oceanografía química
Prime Meridian
Antarctic Intermediate Water
Carbon
Nutrients
Decadal variability
Antarctic
Southern Ocean
The Antarctic
Antarc*
Online Access:http://hdl.handle.net/10553/41427
https://doi.org/10.1007/s10236-018-1131-2
Description
Summary:Antarctic Intermediate Water (AAIW) formation constitutes an important mechanism for the export of macronutrients out of the Southern Ocean that fuels primary production in low latitudes. We used quality-controlled gridded data from five hydrographic cruises between 1990 and 2014 to examine decadal variability in nutrients and dissolved inorganic carbon (DIC) in the AAIW (neutral density range 27 < γn< 27.4) along the Prime Meridian. Significant positive trends were found in DIC (0.70 ± 0.4 μmol kg− 1year− 1) and nitrate (0.08 ± 0.06 μ mol kg− 1year− 1) along with decreasing trends in temperature (− 0.015 ± 0.01∘C year− 1) and salinity (− 0.003 ± 0.002 year− 1) in the AAIW. Accompanying this is an increase in apparent oxygen utilization (AOU, 0.16 ± 0.07 μ mol kg− 1year− 1). We estimated that 75% of the DIC change has an anthropogenic origin. The remainder of the trends support a scenario of a strengthening of the upper-ocean overturning circulation in the Atlantic sector of the Southern Ocean in response to the positive trend in the Southern Annular Mode. A decrease in net primary productivity (more nutrients unutilized) in the source waters of the AAIW could have contributed as well but cannot fully explain all observed changes. 308 295

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