Interannual Variability of Intermediate-Water Circulation in the Northern North Pacific

Abstract:

Interannual variability of intermediate-water circulation in the northern North Pacific was investigated through analysis of potential vorticity evaluated from Argo float data. In the previous studies, it is reported that warm and saline intermediate water is transported from the domain east of Japan to the northern Gulf of Alaska through analysis of climatological data. This current plays an important role in the heat and salt transport in the northern North Pacific. We here focus on the northern edge of this current, which is characterized by the potential vorticity front, to detect the interannual variability of the current. As the result we found that potential vorticity front at the isopycnal surface of 26.8σ_θ, shifted latitudinally 1−2 degrees and 4−5 degrees in the area east and west of 170°W, respectively. This difference would be attributed to the relatively high eddy activity in the area west of 170°W. In the Gulf of Alaska, in the meanwhile, the potential vorticity front shifted zonally, the magnitude of which was 3−4 degrees.