Tides are a fundamental external forcing in coastal oceans, yet their actual long-term variations and underlying mechanisms remain unclear. In this study, we examined the characteristics of long-term changes in tidal amplitude along the Japanese coast, incorporating data from the 2000s onward. Our results show that the four principal tidal constituents have continued to vary since the 2000s, with the semidiurnal M2 and S2 tides exhibiting particularly large decreases in amplitude at locations with originally high tidal ranges—such as the western coast of Kyushu. An analysis of tidal amplitude changes, including those associated with the 18.6-year nodal cycle and the long-term evolution of spring-tide amplitudes, revealed that many stations reached their minimum values after the 2000s. Moreover, numerous coastal sites in Japan have recently experienced historically low tidal amplitudes, underscoring the need to closely monitor potential impacts on the aquatic environment.
"},{"@language":"ja","@value":"潮汐は沿岸海洋の基本的な外力であるが，その長期変化は地域ごとに増減が異なり，原因として地球温暖化，密度成層，海底摩擦，非線形相互作用などが複雑に関係していると考えられているが，それぞれの寄与の程度や空間分布の特徴については未解明な点が多い．本研究では，2000年代以降のデータも含めた日本沿岸域の潮汐振幅の長期変化特性を調べた．その結果，主要４分潮は2000年代以降も変化し続けており，特に半日周潮であるM2潮，S2潮は振幅が大きい九州西岸などでは減少量も大きくなっていた．18.6年周期の変動を含めた潮汐振幅の変化や大潮時の振幅の長期変化を調べた結果，2000年代以降に最小値を示す地点が多く確認された．我が国沿岸において近年が過去最小の潮汐振幅になっている地点も多くあり水環境への影響を注視していく必要がある．
"}],"abstractLicenseFlag":"disallow"}],"creator":[{"@id":"https://cir.nii.ac.jp/crid/1410024725208069760","@type":"Researcher","foaf:name":[{"@language":"ja","@value":"田井 明"},{"@language":"en","@value":"TAI Akira"}],"jpcoar:affiliationName":[{"@language":"ja","@value":"福岡工業大学 社会環境学部社会環境学科"}]},{"@id":"https://cir.nii.ac.jp/crid/1410024725208069761","@type":"Researcher","foaf:name":[{"@language":"ja","@value":"Simon Neill"},{"@language":"en","@value":"NEILL Simon"}],"jpcoar:affiliationName":[{"@language":"ja","@value":"Bangor大学 海洋科学科"}]}],"publication":{"publicationIdentifier":[{"@type":"EISSN","@value":"24366021"}],"prism:publicationName":[{"@language":"ja","@value":"土木学会論文集"},{"@language":"en","@value":"Japanese Journal of JSCE"},{"@language":"ja","@value":"土木学会論文集"},{"@language":"en","@value":"Japanese Journal of JSCE"}],"dc:publisher":[{"@language":"en","@value":"Japan Society of Civil Engineers"},{"@language":"ja","@value":"公益社団法人 土木学会"}],"prism:publicationDate":"2025","prism:volume":"81","prism:number":"17","prism:startingPage":"n/a"},"reviewed":"false","url":[{"@id":"https://www.jstage.jst.go.jp/article/jscejj/81/17/81_25-17083/_pdf"}],"availableAt":"2025","foaf:topic":[{"@id":"https://cir.nii.ac.jp/all?q=Tidal%20Amplitude","dc:title":"Tidal Amplitude"},{"@id":"https://cir.nii.ac.jp/all?q=Long-Term%20Variation%20and%2018.6-Year%20Nodal%20Cycle","dc:title":"Long-Term Variation and 18.6-Year Nodal Cycle"}],"relatedProduct":[{"@id":"https://cir.nii.ac.jp/crid/1360011142938182400","@type":"Article","relationType":["references"],"jpcoar:relatedTitle":[{"@value":"Bootstrap Methods: Another Look at the Jackknife"}]},{"@id":"https://cir.nii.ac.jp/crid/1360011143901002496","@type":"Article","relationType":["references"],"jpcoar:relatedTitle":[{"@value":"A 20th century acceleration in global sea‐level rise"}]},{"@id":"https://cir.nii.ac.jp/crid/1360025034147839744","@type":"Article","relationType":["references"],"jpcoar:relatedTitle":[{"@value":"Technical note: On seasonal variability of the M\n 2\n tide"}]},{"@id":"https://cir.nii.ac.jp/crid/1360306509115188480","@type":"Article","relationType":["references"],"jpcoar:relatedTitle":[{"@value":"Interannual Changes in Tidal Conversion Modulate M2 Amplitudes in the Gulf of Maine"}]},{"@id":"https://cir.nii.ac.jp/crid/1360855570854461568","@type":"Article","relationType":["references"],"jpcoar:relatedTitle":[{"@value":"Fronts in the Irish Sea"}]},{"@id":"https://cir.nii.ac.jp/crid/1360855570894268800","@type":"Article","relationType":["references"],"jpcoar:relatedTitle":[{"@value":"Secular Changes in the Oceanic Tides at Brest, 1711?1936"}]},{"@id":"https://cir.nii.ac.jp/crid/1360869457949806848","@type":"Article","relationType":["references"],"jpcoar:relatedTitle":[{"@value":"Tidal Variability Related to Sea Level Variability in the Pacific Ocean"}]},{"@id":"https://cir.nii.ac.jp/crid/1362544420269079680","@type":"Article","relationType":["references"],"jpcoar:relatedTitle":[{"@value":"Secular changes of the M