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Diapycnal and isopycnal transports in the Southern Ocean estimated by a box inverse model

Citation

Katsumata, K and Sloyan, BM and Masuda, S, Diapycnal and isopycnal transports in the Southern Ocean estimated by a box inverse model, Journal of Physical Oceanography, 43, (11) pp. 2270-2287. ISSN 0022-3670 (2013) [Refereed Article]


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DOI: doi:10.1175/JPO-D-12-0210.1

Abstract

Quantitative descriptions of Circumpolar Deep Water upwelling and evolution into a lighter mode and heavier bottom waters in the Southern Ocean are still not well constrained. Here, data from two occupations of eight hydrographic sections are combined and used in a box inverse model to estimate isopycnal and diapycnal transports in the Southern Ocean. A mixed layer box allows diapycnal transports in the surface mixed layer to be estimated separately. Current velocity at 1000 dbar was constrained by the mean velocity field estimated from subsurface float drift data. The estimated isopycnal transports are largely consistent with past estimates and with outputs of three ocean general circulation models. The estimated subduction and upwelling at the base of the Southern Ocean mixed layer show that Upper Circumpolar Deep Water upwells [16 15 and 17 21 Sv (where 1Sv ≡ 106m3 s-1) by different inversion methods] and evolves into heavier Lower Circumpolar Deep Water (5 13 and 6 18 Sv) and Bottom Water (8 9 and 8 13 Sv) or lighter Mode and Intermediate Waters (9 18 and 13 24 Sv). Meridional transport in the surface mixed layer is due to northward Ekman transport and mostly southward eddy transport. In seasonal ice-covered areas near Antarctica, a significant (14 ±14 Sv) southward transport was found. The southward eddy transport is largest north of the Antarctic Circumpolar Current and decreases poleward because of the poleward decrease in the eddy diffusivity. The interior diapycnal transports, which can be either upward (gaining buoyancy) or downward (gaining density), are comparable in magnitude to the horizontal diapycnal transports within the surface mixed layer.

Item Details

Item Type:Refereed Article
Keywords:inverse methods, meridional overturning circulation, mixed layer, mixing, Southern Hemisphere, upwelling/downwelling
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical Oceanography
Objective Division:Environment
Objective Group:Other Environment
Objective Field:Marine Oceanic Processes (excl. climate related)
Author:Sloyan, BM (Dr Bernadette Sloyan)
ID Code:119106
Year Published:2013
Web of Science® Times Cited:3
Deposited By:Sustainable Marine Research Collaboration
Deposited On:2017-07-26
Last Modified:2017-10-16
Downloads:0

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