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Hokkaido University Collection of Scholarly and Academic Papers >
Graduate School of Fisheries Sciences / Faculty of Fisheries Sciences >
北海道大学水産科学研究彙報 = Bulletin of Fisheries Sciences, Hokkaido University >
第74巻 第1号 >
津軽海峡西口の浅瀬地形上通過流による水塊再配置と鉛直混合
| Title: | 津軽海峡西口の浅瀬地形上通過流による水塊再配置と鉛直混合 |
| Other Titles: | Water mass redistribution and consequent vertical mixing due to passage-flow over the sill-topography at the western entrance of the Tsugaru Strait |
| Authors: | 山根, 斗和1 Browse this author | | 磯田, 豊2 Browse this author →KAKEN DB | | 西岡, 優3 Browse this author | | 越後, 友利果4 Browse this author | | 藤居, 流5 Browse this author | | 脇田, 昌英6 Browse this author →KAKEN DB | | 山崎, 友資7 Browse this author | | 小林, 直人8 Browse this author →KAKEN DB | | 飯田, 高大9 Browse this author →KAKEN DB | | 金子, 仁10 Browse this author |
| Authors(alt): | Yamane, Towa1 | | Isoda, Yutaka2 | | Nishioka, Yu3 | | Echigo, Yurika4 | | Fujii, Yu5 | | Wakita, Masahide6 | | Yamazaki, Tomoyasu7 | | Kobayashi, Naoto8 | | Iida, Takahiro9 | | Kaneko, Hitoshi10 |
| Keywords: | Tsugaru Strait | | Japan Sea Intermediate Water (JSIW) | | sill-topography | | stratified fluid | | pseudo-bottom Ekman flow |
| Issue Date: | 4-Aug-2024 |
| Publisher: | 北海道大学大学院水産科学研究院 |
| Journal Title: | 北海道大学水産科学研究彙報 |
| Journal Title(alt): | Bulletin of Fisheries Sciences, Hokkaido University |
| Volume: | 74 |
| Issue: | 1 |
| Start Page: | 35 |
| End Page: | 58 |
| Abstract: | Extensive hydrographic observations traversing the Tsugaru Strait using a research vessel were carried out in spring 2021 and summer 2022. In both seasons, in addition to the inflow of Tsushima Warm Current Water from the western entrance of the strait, water mass originating in the middle layer of the Japan Sea, i.e., Japan Sea Intermediate Water (JSIW), intruded into the strait from the bottom layer on the Hokkaido (northern) side. In the downstream of the sill-topography located at the western entrance, density stratification rapidly weakened, concurrently with disappearance of JSIW properties. In order to investigate key physical drivers of the observed water mass distribution and its modification, the numerical experiments were conducted on stratified fluid passing over a trapezoidal-shaped sill feature in the channel model with a simple rectangular cross section. Even without the sill, vertical circulation, which is accompanied by upwelling along Hokkaido (northern) coast and density inversion near the sea bottom, is formed by the northward bottom Ekman flow caused by the eastward passage-flow. When the silltopography is added to this, vertical circulation is further enhanced by driving of“ pseudo-bottom Ekman flow” on both its upstream and downstream slopes. Near the Hokkaido (northern) coast in the downstream of the sill, offshore (southward) surface flow connected to coastal upwelling moves the velocity maximum of the passage-flow to the Aomori (southern) side. Density inversion reaching the sea surface from the sea bottom expanded off Hokkaido (northern) coast locally, and the gravitationally unstable vertical mixing occurred there. These results suggest that sill-topography promotes water mass redistribution and local vertical mixing associated with vertical circulation on the transverse section, resulting in active water mass modification even in short channels such as the Tsugaru Strait. |
| Type: | bulletin (article) |
| URI: | http://hdl.handle.net/2115/92924 |
| Appears in Collections: | 北海道大学水産科学研究彙報 = Bulletin of Fisheries Sciences, Hokkaido University > 第74巻 第1号
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