Formation and Conservation of a polynya in the Weddell Sea.

Timmermann, R., Lemke, Peter and Kottmeier, C. (1999) Formation and Conservation of a polynya in the Weddell Sea. Open Access Journal of Physical Oceanography, 29 (6). pp. 1251-1264. DOI 10.1175/1520-0485(1999)029<1251:FAMOAP>2.0.CO;2.

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A dynamic–thermodynamic sea ice–mixed layer model for the Weddell Sea is complemented by a simple, diagnostic model to account for local sea ice–atmosphere interaction. To consider the atmospheric influence on the oceanic mixed layer, the pycnocline upwelling velocity is calculated using the theory of Ekman pumping. In several experiments, formation and conservation of a polynya in the Weddell Sea are investigated. Intrusion of heat into the lower atmosphere above the polynya area is assumed to cause a thermal perturbation and a cyclonic thermal wind field. Superposed with daily ECMWF surface winds, this modified atmospheric forcing field intensifies oceanic upwelling and induces divergent ice drift. Simulation results indicate that in case of a weak atmospheric cross-polynya flow the formation of a thermal wind field can significantly extend the lifetime of a large polynya. The repeated occurrence of the Weddell polynya in the years 1974–76 thus appears to be an effect of feedback mechanisms between sea ice, atmosphere, and oceanic mixed layer.

Document Type: Article
Research affiliation: OceanRep > Institute for Marine Science Kiel
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1175/1520-0485(1999)029<1251:FAMOAP>2.0.CO;2
ISSN: 0022-3670
Date Deposited: 18 Feb 2008 17:24
Last Modified: 06 Apr 2018 09:01

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