北太平洋亜寒帯循環に及ぼす天皇海山列の影響 : 天皇海山列東側境界流量機構

概要

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To make clear bathymetric influences of the Emperor Seamounts upon the North Pacific subarctic gyre, numerical experiments were performed using two-layer model with an idealized wind and ridge. Seasonally varying interior Sverdrup transport to the east of the ridge partly returns along the eastern side of the ridge as a western boundary current. A ratio of the boundary transport to the interior transport depends on a ridge height (H_R) and stratification (N). For smaller H_R (H_R/H_0 < 0.3 where H_0 is background water depth), the ratio increases with H_R, but it changes little with N. For larger H_R (HR_/H_0 > 0.3), the ratio decreases with N but is independent of H_R, Spatial distribution of geostrophic contours is a key to understand the dependence of the ratio on H_R and N. For smaller H_R, the ratio almost coinsides with a ratio of the number of closing geostrophic contours to one of all geostrophic contours. For larger H_R at which all geotstrophic contours in the eastern region cannot cross over the ridge, bottom pressure torque decreases with N to allow more transport across the ridge.27
Research Institute for Applied Mechanics, Kyushu University,九州大学応用力学研究所の論文