Interaction between the northern North Pacific and its marginal seas
Takatoshi Takizawa
Japan Marine Science and Technology Center
2-15, Natsushima, Yokosuka 237, JAPAN
1. Introduction
Regarding Subarctic Gyre, the North Pacific has two important marginal seas; the Okhotsk Sea and the Bering Sea. They are the site of more active thermohaline forcing than the North Pacific. The cooling, sea ice production and river runoff in these seas contribute to water mass formations and modifications of the surface and intermediate water properties of the northern North Pacific.
The marginal Seas border island chains and communicate with the North Pacific through straits or passes. The subarctic gyre has strong flows along the North Pacific flank of these island chains. The thermohaline and biogeochemical structure of these seas are linked to the North Pacific, but, little is known about the rates, and their variations of mass and property exchanges. Even less is known about the processes that control flow through the passes. The general circulation path is evident from the distribution of water properties and numerical modeling results. However, recent observations indicate that the flows of subarctic gyre are highly variable as eddies and meanders frequently occur. Furthermore, transport through the straits/passes can vary considerably in response to wind stress fluctuations, flow variations in the gyre and tidal currents.
2. Bering Sea
Exchange between the North Pacific and the Bering Sea occurs through passes comprising the Aleutian Island arc. The Alaskan Stream, the northern limb of the subarctic gyre, flows westward along the south side of Amchitka Pass (Fig.1). A portion of this current flows northward through the
