A Possible Feedback Mechanism Involving the Arctic Freshwater,the Arctic Sea Ice,and the North Atlantic Drift

作     者：Odd Helge OTTER Helge DRANGE 

作者机构：Nansen Environmental and Remote Sensing Center Edv. Griegsvei 3A5059 Bergen Bjerknes Centre for Climate Research Allégt. 55 5007 BergenNansen Environmental and Remote Sensing Center Edv. Griegsvei 3A5059 Bergen Bjerknes Centre for Climate Research Allégt. 55 5007 BergenGeophysical Institute University of Bergen Allégt. 70 5007 Bergen Nansen-Zhu International Research Centre Beijing 100029 

出 版 物：《Advances in Atmospheric Sciences》 (大气科学进展（英文版）)

年 卷 期：2004年第21卷第5期

页      面：784-801页

核心收录：

学科分类：07[理学] 0705[理学-地理学] 070501[理学-自然地理学] 

基　　金：Research Council of Norway through Project 

主　　题：Arctic Ocean freshwater seaice North Atlantic Drift 

摘      要：Model studies point to enhanced warming and to increased freshwater ?uxes to high northern latitudes in response to global warming. In order to address possible feedbacks in the ice-ocean system in response to such changes, the combined e?ect of increased freshwater input to the Arctic Ocean and Arctic warming—the latter manifested as a gradual melting of the Arctic sea ice—is examined using a 3-D isopycnic coordinate ocean general circulation model. A suite of three idealized experiments is carried out: one control integration, one integration with a doubling of the modern Arctic river runo?, and a third more extreme case, where the river runo? is ?ve times the modern value. In the two freshwater cases, the sea ice thickness is reduced by 1.5–2 m in the central Arctic Ocean over a 50-year period. The modelled ocean response is qualitatively the same for both perturbation experiments: freshwater propagates into the Atlantic Ocean and the Nordic Seas, leading to an initial weakening of the North Atlantic Drift. Furthermore, changes in the geostrophic currents in the central Arctic and melting of the Arctic sea ice lead to an intensi?ed Beaufort Gyre, which in turn increases the southward volume transport through the Canadian Archipelago. To compensate for this southward transport of mass, more warm and saline Atlantic water is carried northward with the North Atlantic Drift. It is found that the increased transport of salt into the northern North Atlantic and the Nordic Seas tends to counteract the impact of the increased freshwater originating from the Arctic, leading to a stabilization of the North Atlantic Drift.