Formation of the Terra Nova Bay: polynya and climatic implications
Gallée, H. (1997). Formation of the Terra Nova Bay: polynya and climatic implications, in: Caschetto, S. (Ed.) Belgian research programme on the Antarctic: scientific results of phase III (1992-1996): 3. Glaciology and climatology. pp. A3/10/001/1-36
In: Caschetto, S. (Ed.) (1997). Belgian research programme on the Antarctic: scientific results of phase III (1992-1996): 3. Glaciology and climatology. Belgian scientific research programme on Antarctica. Federal Office for Scientific, Technical and Cultural Affairs: Brussel. 149 pp., more
In: Belgian scientific research programme on Antarctica. Belgian Science Policy Office: Brussel. , more
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| Abstract |
In this paper one presents a preliminary simulation of the Terra Nova Bay polynya by a coupled atmosphere-polynya model. The atmospheric model is a hydrostatic primitive equations model that has been validated previously by a simulation of the strong katabatic winds observed in this area. The polynya model includes a representation of the free drift of frazil ice, and simple sea-ice dynamics and thermodynamics. Two-dimensional and three-dimensional experiments have been performed under polar night conditions. Two-dimensional experiments show that an open (warm) water area influences significantly the atmospheric circulation in the antarctic coastal zone: an additional ice-breeze effect is simulated and is responsible for the strenghthening of the katabatic winds near the coast. Because of the important temperature difference (up to 40°C) between the continental air and the ice-free ocean, strong heat fluxes from the polynya surface are simulated. Finally a three-dimensional experiment has been performed including Terra Nova Bay. The polynya observed in this region is well reproduced. It is found that heat losses from the polynya surface are stronger than previously estimated but are probably constrained by the idealized representation of frazil ice, which is assumed to be uniform in each grid box. This stresses the need for having a better knowledge of frazil ice evolution in large polynyas. A consequence of the strong heat losses from antarctic coastal polynyas like that of Terra Nova Bay is that they have an impact on the energy and momentum budgets of the atmosphere around Antarctica and influence subsequently the atmospheric general circulation and the Earth's climate. Another consequence of the strong heat release from the ocean in antarctic coastal polynyas is an enhanced sea-ice formation and a subsequent salt rejection in the water column. For example, sea-ice formation in the Terra Nova Bay polynya could contribute to roughly 10% of the total sea-ice formation in the region of the Ross Sea continental shelf. Rejected salt could contribute to the formation of coastal dense water and ultimately to the formation of the antarctic bottorn water . |
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