open access

https://doi.org/10.14943/bull.fish.76.24

https://hdl.handle.net/2115/100329

Shallow-Water Tides Excited Synchronously with the Spring/Neap Tidal Cycles in the Tsugaru Strait

日本語

Numerical experiment

2026-09-01

北海道大学大学院水産科学研究院

Bulletin of Fisheries Sciences, Hokkaido University

76

24-38

15

After mathematically explaining the periodicity and amplitude modulation of shallow-water tides (over-tide and compound tide) resulting from the combination of four major astronomical tides (K1, O1, M2, and S2), these characteristics were found in the coastal sea level records (Hakodate, Shimokita, and Tappi) in the Tsugaru Strait. Numerical experiments on realistic topography around the strait are carried out to identify where shallow-water tides excite. The forcing of this model is both of the passage flow through the strait and the four major tidal curents, reproduced by sea level oscillations at the western and eastern open boundaries. The shallow-water tides were excited near the narrowing areas, and the observed periodical cycles of 8-hour and 6-hour at Tappi were explained as being linked to the spring/neap tides. If nonlinearity is dominant, the four major astronomical tides in any ocean may all be contaminated by shallow-water tides. For example, compound tide generating from diurnal tides K1 and O1 (denoted as M2’ in this study) is excited with exactly the same period as the astronomical tide M2. Using the same model, we demonstrated that M2’ signal with nearly opposite phase overlapped with the true M2 signal at the narrowing areas.

紀要論文

Version of Record

2435-3353