HR: 0800h
AN: OS41A-0466    [Abstracts]
TI: Intensification of the Atlantic Deep Circulation by the Canadian Archipelago Throughflow
AU: * Komuro, Y
EM: komuro@ccsr.u-tokyo.ac.jp
AF: Center for Climate System Research, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904 Japan
AU: Hasumi, H
EM: hasumi@ccsr.u-tokyo.ac.jp
AF: Center for Climate System Research, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904 Japan
AB: In the northern high latitudes, where deep water formation occurs, horizontal freshwater transport in the form of seawater and sea ice is a major component of the freshwater budget. The horizontal freshwater transport controls the surface salinity in this region, and thus has a significant impact on the deep water formation process and the resultant Atlantic deep circulation. In this study, we focus on the freshwater transport through the Canadian Archipelago, and investigate how the intensity of the Atlantic deep circulation depend on opening and closing of the Canadian Archipelago. An ice-ocean coupled model is used; it consists of the oceanic component COCO3 (CCSR Ocean Component Model version 3) and the sea ice component including dynamics and thermodynamics. The horizontal resolution is 1 degree. Restoring surface salinity to observed data is not employed. When the Canadian Archipelago is opened, the Atlantic deep circulation strengthens by 21 %. The deep water formation in the northern North Atlantic is responsible for the enhancement. The flow of a low salinity water through the Canadian Archipelago does not directly affect the deep water formation in the northern North Atlantic, since it flows only in the western part of the Labrador Sea. The confinement of the flow in the western Labrador Sea is caused by the reproduction of the cyclonic circulation there. Instead, the surface salinity in the deep water formation region is affected by the East Greenland Current, which flows from the Fram Strait along the east coast of Greenland and increases its salinity by opening the Canadian Archipelago. Consequently, the deep water formation is activated there and the Atlantic deep circulation strengthens. Thus, it is suggested that the Canadian Archipelago throughflow does not directly suppress the deep water formation in the northern North Atlantic, but indirectly activate it by the increase in salinity of the East Greenland Current.
DE: 4207 Arctic and Antarctic oceanography
DE: 4255 Numerical modeling
DE: 4532 General circulation
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting