Abstract
Abstract. We describe the seasonal and interannual variability of volume transports in the Weddell and Ross Seas using the 1/12° 20-yr simulation of the OCCAM global ocean general circulation model. The average simulated full-depth cumulative volume transports were 28.5 ± 2.9 Sv (1 Sv ≡ 106 m3 s−1) and 13.4 ± 5.2 Sv, across the main export regions of the Weddell and Ross Seas, respectively. The values of mean outflow of Antarctic Bottom Water (AABW) (defined by neutral density γn ≥ 28.27 kg m−3) from the Weddell and Ross Seas of 10.6 ± 3.1 Sv and 0.5 ± 0.7 Sv, respectively, agree with the range reported in historical observational studies. The export of Weddell Sea dense water in OCCAM is primarily determined by the strength of the Weddell Gyre. Variability in AABW export is predominantly at periods of ~1 yr and 2–4 yr.
Highlights
During the fourth International Polar Year (IPY; 2007–2009), the scientific community focused on better understanding the interactions between ocean, atmosphere, and cryosphere, and the role and susceptibility of polar regions in a climate change scenario
We have shown that Ocean Circulation and Climate Advanced Modelling (OCCAM) simulates an average Antarctic Bottom Water (AABW) (i.e. γ n ≥ 28.27 kg m−3) outflow of ∼11 Sv from the northwestern Weddell Sea and only ∼1 Sv from the Ross Sea
In the Weddell Sea, the 2–4 yr period is consistent with the time scale of observed changes in the atmosphere, sea ice, and ocean surface (Venegas and Drinkwater, 2001), which are directly linked to the processes of AABW formation
Summary
During the fourth International Polar Year (IPY; 2007–2009), the scientific community focused on better understanding the interactions between ocean, atmosphere, and cryosphere, and the role and susceptibility of polar regions in a climate change scenario. OCCAM is a global ocean general circulation model (OGCM) (Coward and de Cuevas, 2005) coupled with a dynamic-thermodynamic sea ice model (Aksenov, 2002) Such a sea ice model is essential to reproduce AABW properties in OGCMs (Kerr et al, 2009b), because both dynamic and thermodynamic sea ice processes play significant roles in Southern Ocean climate variability and bottom water formation A detailed assessment of the OCCAM 1/12◦ simulation regarding the representation of physical properties in the Weddell Sea was discussed by Renner et al (2009) They highlighted that the choice of model must be made carefully and according to the purpose of the study.
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