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An assessment of Southern Ocean water masses and sea ice during 19882007 in a suite of interannual CORE-II simulations

Citation

Downes, SM and Farneti, R and Uotila, P and Griffies, SM and Marsland, SJ and Bailey, D and Behrens, E and Bi, D and Biastoch, A and Boning, C and Bozec, A and Canuto, VM and Chassignet, E and Danabasoglu, G and Danilov, S and Diansky, N and Drange, H and Fogli, PG and Gusev, A and Howard, A and Ilicak, M and Jung, T and Kelley, M and Large, WG and Leboissetier, A and Long, M and Lu, J and Masina, S and Mishra, A and Navarra, A and Nurser, AJG and Patara, L and Samuels, BL and Sidorenko, D and Spence, P and Tsujino, H and Wang, Q and Yeager, SG and Bentsen, M, An assessment of Southern Ocean water masses and sea ice during 1988-2007 in a suite of interannual CORE-II simulations, Ocean Modelling, 94 pp. 67-94. ISSN 1463-5003 (2015) [Refereed Article]

Copyright Statement

Copyright 2015 Elsevier Ltd.

DOI: doi:10.1016/j.ocemod.2015.07.022

Abstract

We characterise the representation of the Southern Ocean water mass structure and sea ice within a suite of 15 global ocean-ice models run with the Coordinated Ocean-ice Reference Experiment Phase II (CORE-II) protocol. The main focus is the representation of the present (19882007) mode and intermediate waters, thus framing an analysis of winter and summer mixed layer depths; temperature, salinity, and potential vorticity structure; and temporal variability of sea ice distributions. We also consider the interannual variability over the same 20 year period. Comparisons are made between models as well as to observation-based analyses where available.

The CORE-II models exhibit several biases relative to Southern Ocean observations, including an underestimation of the model mean mixed layer depths of mode and intermediate water masses in March (associated with greater ocean surface heat gain), and an overestimation in September (associated with greater high latitude ocean heat loss and a more northward winter sea-ice extent). In addition, the models have cold and fresh/warm and salty water column biases centred near 50S. Over the 19882007 period, the CORE-II models consistently simulate spatially variable trends in sea-ice concentration, surface freshwater fluxes, mixed layer depths, and 200700 m ocean heat content. In particular, sea-ice coverage around most of the Antarctic continental shelf is reduced, leading to a cooling and freshening of the near surface waters. The shoaling of the mixed layer is associated with increased surface buoyancy gain, except in the Pacific where sea ice is also influential. The models are in disagreement, despite the common CORE-II atmospheric state, in their spatial pattern of the 20-year trends in the mixed layer depth and sea-ice.

Item Details

Item Type:Refereed Article
Keywords:CORE-II experiments, Southern Ocean, water masses, sea ice, ocean model intercomparison,
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical Oceanography
Objective Division:Environment
Objective Group:Climate and Climate Change
Objective Field:Climate Change Models
UTAS Author:Downes, SM (Dr Stephanie Downes)
ID Code:103137
Year Published:2015
Web of Science® Times Cited:40
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2015-09-22
Last Modified:2017-11-17
Downloads:0

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