Authors: Katsuro Katsumata Ichiro Yasuda
Publish Date: 2010/07/25
Volume: 66, Issue: 4, Pages: 489-504
Abstract
The outflow from the Sea of Okhotsk to the North Pacific is important in characterising the surfacetointermediatedepth water masses in the Pacific Ocean The two basins are separated by the Kuril Islands with numerous straits among which the Bussol and the Kruzenshterna Straits are deeper than 1000 m The physics governing the transport between the two basins is complicated but when the semidiurnal and diurnal tides are subtracted the observed density and velocity structures across the Bussol Strait suggest a significant contribution from geostrophic balance Using a twolayer model with the interface at 275σ θ part of the upper layer transport that is not driven by tides is estimated using two previously unexplored data sets outputs from the Ocean General Circulation Model for Earth Simulator OFES and historical hydrographic data The Pacific water flows into the Sea of Okhotsk through the northeastern straits The greatest inflow is through the Kruzenshtern Strait but the OFES results show that the contributions from other shallower straits are almost half of the Kruzenshtern inflow Similarly the outflow from the Sea of Okhotsk is through the southwestern straits of the Kuril Islands with the largest Bussol Strait contributing 60 of the total outflow The OFES and hydrographic estimates agree that the exchange is strongest in February to March with an inflow of about −6 to −12 Sv negative indicates the flow from the North Pacific 1 Sv = 106 m3s−1 and an outflow from the Sea of Okhotsk of about +8 to +9 Sv positive indicates the flow from the Sea of Okhotsk which is weakest in summer −3 to +1 Sv through the northeastern straits and +0 to +3 Sv through the southwestern straits The estimated seasonal variation is consistent with a simple analytic model driven by the difference in sea surface height between the two basins
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