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dc.contributor.authorKobayashi, Shihoen
dc.contributor.authorNagao, Kentaroen
dc.contributor.authorTsurushima, Daikien
dc.contributor.authorSasakura, Satoshien
dc.contributor.authorFujiwara, Tatekien
dc.contributor.alternative小林, 志保ja
dc.contributor.alternative藤原, 建紀ja
dc.description.abstractEstuarine circulation is a vertical circulation that develops along the salinity gradient in estuaries and nearshore coastal waters. Fresher, and therefore less-dense, water flows out of the estuary in the surface layer, while a deeper inflow brings water from the open sea into the estuary. This study uses 7 years of in situ current measurements and hydrographic surveys to verify that this deeper inflow has two modes: a deep inflow that intrudes along the seabed, and a shallow-inflow that penetrates into the subsurface layer. These modes show seasonal variability, i.e., the deep-inflow mode occupies almost all of the winter season, whereas the shallow-inflow mode dominates during the summer. This mode change may play a key role in oxygen and carbon dioxide (CO₂) dynamics in estuaries and nearshore coastal waters. When the transition from deep- to shallow-inflow begins in spring, a cold water mass forms on the seabed in the upper estuary. This cold water mass is isolated from heating sources and oxygenated water; consequently, the cold water mass becomes hypoxic and accumulates both inorganic nutrients and CO₂ during spring and summer. When the transition from the shallow- to deep-inflow occurs, the CO₂, which is trapped in the bottom-water, is emitted to the atmosphere. The mechanism that causes the seasonal mode change in estuarine circulation is driven by the spatial inhomogeneity in the heating or cooling of the lower layer, which generates a horizontal density gradient in the layer. This mechanism highlights the importance of temperature in estuarine dynamics, which has not been extensively studied previously.en
dc.publisherSpringer Natureen
dc.rightsThis is a post-peer-review, pre-copyedit version of an article published in 'Estuaries and Coasts'. The final authenticated version is available online at: 10.1007/s12237-021-00991-6.en
dc.rightsThe full-text file will be made open to the public on 7 October 2022 in accordance with publisher's 'Terms and Conditions for Self-Archiving'.en
dc.rightsThis is not the published version. Please cite only the published version. この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。en
dc.subjectEstuarine circulationen
dc.subjectInflow depthen
dc.subjectCarbon dynamicsen
dc.subjectIse Bayen
dc.titleSeasonal Changes of Estuarine Gravitational Circulation: Response to the Annual Temperature Changeen
dc.typejournal article-
dc.type.niitypeJournal Article-
dc.identifier.jtitleEstuaries and Coastsen
dcterms.accessRightsopen access-
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