Oxygen in the Southern Ocean From Argo Floats: Determination of Processes Driving Air-Sea Fluxes

Type Article
Date 2017-11
Language English
Author(s) Bushinsky Seth M.1, Gray Alison R.1, 2, Johnson Kenneth S.3, Sarmiento Jorge L.1
Affiliation(s) 1 : Princeton Univ, Atmospher & Ocean Sci, Princeton, NJ 08544 USA.
2 : Univ Washington, Sch Oceanog, Seattle, WA 98195 USA.
3 : Monterey Bay Aquarium Res Inst, Moss Landing, CA USA.
Source Journal Of Geophysical Research-oceans (2169-9275) (Amer Geophysical Union), 2017-11 , Vol. 122 , N. 11 , P. 8661-8682
DOI 10.1002/2017JC012923
WOS© Times Cited 37
Note This article also appears in: The Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) Project: Technologies
Keyword(s) air-sea oxygen fluxes, Argo profiling floats, Southern Ocean seasonal cycles

The Southern Ocean is of outsized significance to the global oxygen and carbon cycles with relatively poor measurement coverage due to harsh winters and seasonal ice cover. In this study, we use recent advances in the parameterization of air-sea oxygen fluxes to analyze 9 years of oxygen data from a recalibrated Argo oxygen data set and from air-calibrated oxygen floats deployed as part of the Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project. From this combined data set of 150 floats, we find a total Southern Ocean oxygen sink of -18380 Tmol yr(-1) (positive to the atmosphere), greater than prior estimates. The uptake occurs primarily in the Polar-Frontal Antarctic Zone (PAZ, -9430 Tmol O-2 yr(-1)) and Seasonal Ice Zone (SIZ, -1119.3 Tmol O-2 yr(-1)). This flux is driven by wintertime ventilation, with a large portion of the flux in the SIZ passing through regions with fractional sea ice. The Subtropical Zone (STZ) is seasonally driven by thermal fluxes and exhibits a net outgassing of 4729 Tmol O-2 yr(-1) that is likely driven by biological production. The Subantarctic Zone (SAZ) uptake is -25 +/- 12 Tmol O-2 yr(-1). Total oxygen fluxes were separated into a thermal and nonthermal component. The nonthermal flux is correlated with net primary production and mixed layer depth in the STZ, SAZ, and PAZ, but not in the SIZ where seasonal sea ice slows the air-sea gas flux response to the entrainment of deep, low-oxygen waters.

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