pass and, on the Bering Sea side, turns eastward to flow along the north side of the Aleutian Islands as the North Aleutian Current (NAC). This circulation path is evident from the distribution of water properties, drifter trajectories and numerical model results. Observations from the Bering Sea indicate that these currents quite variable as eddies and meanders frequently occur. Similarly, transport through some of the passes can change markedly in response to wind stress fluctuations or flow variations in the Alaskan Stream.
Figure 2 is monthly maps of the SSHa (Sea Surface Height anomaly) field showing the Alaskan Stream eddy, flow through Amchitka Pass, and circulation in the Aleutian Basin. Map of June 1987 suggests that circulation in the southern Aleutian Basin is more cyclonic and flow through the pass is southward. We can see an anomaly moved from east to west. Map of December 1987 suggests circulation in the Aleutian Basin has become anomalously anticyclonic. Independent current-meter records of Amchitka Pass in Amchitka Pass from June 1987 to June 1988 indicate that there is a northward component of flow through the pass. Southward flow begins in July 1987 and continues until October 1987 when it reverses to flow northward again (Fig.3). The comparison of maps of SSHa in the Bering Sea region with current meter records indicate that flow through Amchitka Pass responds to the transit of a large eddy in the Alaskan Stream south of the pass.
3. Okhotsk Sea
It is generally understood that the subarctic North Pacific region plays an important role in climate change through the processes, such as formation of North Pacific Intermediate Water and uptake of CO2. However, we have little knowledge about the water mass formation and modification mechanisms along the subarctic gyre.
From 1993 WOCE section in the Okhotsk Sea, Wong (1996) presents a model of the formation of the Intermediate Water (Fig.4). The dense winter waters would sink and mix with surrounding waters forming a shelf-derived water (SDW). This SDW would mix with the North Pacific water entering Okhotsk Sea through Kruzenshterna Strait to produce the Sea of Okhotsk
