{"title":"Vortex pairs formed by tidal currents in the Naruto Strait: effects of bottom topography, density stratification, and coastline geometry","authors":"","doi":"10.1007/s10872-023-00709-1","DOIUrl":null,"url":null,"abstract":"<h3>Abstract</h3> <p>Vortex pairs formed at a strait outlet by tidal flow effectively induce water exchange and material transport in coastal areas. However, the effects of complex bottom topography and density stratification remain unclear. Here, we investigated the development and propagation of vortex pairs in the Naruto Strait, which has complex topography. Satellite observations indicated that the vortex pairs formed on the northern side of the strait continue to move away from the strait after the reversal of tidal flow, shifting their propagation from northward to westward. Numerical experiments revealed that: (1) changes in depth affect the propagation speed and overall size of vortex pairs; (2) density stratification reduces the effects of depth changes; (3) coastline geometry affects the propagation direction of vortex pairs. Furthermore, experiments with idealized topography showed that in a region where depth increases with vortex-pair propagation, the jet decelerates, and the vortex pair shrinks in size. Conversely, in a region where depth decreases, the jet widens, and the vortex pair expands. The changes in jet flow speed can be attributed to flow continuity and depth change, as the latter alters the cross-sectional area. Meanwhile, the changes in vortex pair size and jet width can be explained by vortex propagation on a slope due to potential vorticity conservation. These effects of topography and density stratification may also be significant in other coastal areas and potentially influence the Strouhal number threshold below which vortex pairs leave an outlet.</p>","PeriodicalId":16640,"journal":{"name":"Journal of Oceanography","volume":null,"pages":null},"PeriodicalIF":1.3000,"publicationDate":"2023-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Oceanography","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1007/s10872-023-00709-1","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"OCEANOGRAPHY","Score":null,"Total":0}
引用次数: 0
Abstract
Vortex pairs formed at a strait outlet by tidal flow effectively induce water exchange and material transport in coastal areas. However, the effects of complex bottom topography and density stratification remain unclear. Here, we investigated the development and propagation of vortex pairs in the Naruto Strait, which has complex topography. Satellite observations indicated that the vortex pairs formed on the northern side of the strait continue to move away from the strait after the reversal of tidal flow, shifting their propagation from northward to westward. Numerical experiments revealed that: (1) changes in depth affect the propagation speed and overall size of vortex pairs; (2) density stratification reduces the effects of depth changes; (3) coastline geometry affects the propagation direction of vortex pairs. Furthermore, experiments with idealized topography showed that in a region where depth increases with vortex-pair propagation, the jet decelerates, and the vortex pair shrinks in size. Conversely, in a region where depth decreases, the jet widens, and the vortex pair expands. The changes in jet flow speed can be attributed to flow continuity and depth change, as the latter alters the cross-sectional area. Meanwhile, the changes in vortex pair size and jet width can be explained by vortex propagation on a slope due to potential vorticity conservation. These effects of topography and density stratification may also be significant in other coastal areas and potentially influence the Strouhal number threshold below which vortex pairs leave an outlet.
期刊介绍：
The Journal of Oceanography is the official journal of the Oceanographic Society of Japan and open to all oceanographers in the world. The main aim of the journal is to promote understandings of ocean systems from various aspects including physical, chemical, biological, geological oceanography as well as paleoceanography, etc. The journal welcomes research focusing on the western North Pacific and Asian coastal waters, but the study region is not limited to the Asian Pacific. The journal publishes original articles, short contributions, reviews, and correspondence in oceanography and related fields.
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