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Dense shelf water formation and brine-driven circulation in the Adélie and George V Land region
journal contribution
posted on 2023-05-18, 20:34 authored by Kusahara, K, Hasumi, H, Guy WilliamsThe formation and outflow of dense shelf water (DSW) from the Adélie and George V Land region and the seasonal variation in the ocean circulation therein are investigated using a global ice-ocean model with fine resolution around East Antarctica. The model reproduces key elements of the overall system described by previous observational studies: modified Circumpolar Deep Water intrusions into the Adélie Depression, enhanced sea-ice production in the coastal polynya regime, and seasonal variation in the export of DSW through the Adélie Sill. We find two distinct seasonal circulation patterns in the Adélie Depression. The first is a vertical circulation formed over the southwestern flank of the Mertz Bank in winter, with a southeastward inflow of light water in the upper layer and a northwestward outflow of dense water in the lower layer. The second is a surface-intensified clockwise circulation trapped in the Adélie Depression during summer. This seasonal variation is attributed to the spinning-up and down of the haline circulation which is driven by the brine-rejection from enhanced sea ice formation in the coastal polynyas. In the model a similar haline circulation also develops in the Mertz Depression. Assuming a critical density of 27.88 (27.80) kg m−3 for outflowing DSW, the annual mean export from the Adélie and Mertz Sills are 0.21 (0.37) Sv and 0.12 (0.32) Sv, respectively. The model clearly shows a dual-system for DSW formation and export from the Adélie and Mertz Depressions, consistent with recent observational analysis over the continental slope and rise.
History
Publication title
Ocean ModellingVolume
37Issue
3-4Pagination
122-138ISSN
1463-5003Department/School
Institute for Marine and Antarctic StudiesPublisher
Elsevier Sci LtdPlace of publication
The Boulevard, Langford Lane, Kidlington, Oxford, England, Oxon, Ox5 1GbRights statement
Copyright 2011 ElsevierRepository Status
- Restricted