TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 58 (No. 6), pp. 851-860, 2001

Barotropic Response of the Sea of Okhotsk to Wind Forcing

Daisuke Simizu1* and Kay I. Ohshima2

1Graduate School of Environmental Earth Science, Hokkaido University, Sapporo 060-0810, Japan
2Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan

(Received 25 October 2001; in revised form 16 April 2002; accepted 17 April 2002)

Abstract: We have examined wind-induced circulation in the Sea of Okhotsk using a barotropic model that contains realistic topography with a resolution of 9.25 km. The monthly wind stress field calculated from daily European Centre for Medium-Range Weather Forecasting (ECMWF) Re-Analysis data is used as the forcing, and the integration is carried out for 20 days until the circulation attains an almost steady state. In the case of November (a representative for the winter season from October to March), southward currents of velocity 0.1-0.3 m s-1 occur along the bottom contours off the east of Sakhalin Island. The currents are mostly confined to the shelf (shallower than 200 m) and extend as far south as the Hokkaido coast. In the July case (a representative for the summer season from April to September), significant currents do not occur, even in the shallow shelves. The simulated southward current over the east Sakhalin shelf appears to correspond to the near-shore branch of the East Sakhalin Current (ESC), which was observed with the surface drifters. These seasonal variations simulated in our experiments are consistent with the observations of the ESC. Dynamically, the simulated ESC is interpreted as the arrested topographic wave (ATW), which is the coastally trapped flow driven by steady alongshore wind stress. The volume transport of the simulated ESC over the shelf reaches about 1.0 Sv (1 Sv = 106 m3s-1) in the winter season, which is determined by the integrated onshore Ekman transport in the direction from which shelf waves propagate.

*Corresponding author E-mail: dais@lowtem.hokudai.ac.jp

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