Hiroya Kinoshita, Hideki Hoshi, Youichi Atsumi, Shin-ichiro Sekiguchi, Toshihiko Yamashita


Studies of flows near the coast from the viewpoint of coastal engineering have focused on tidal currents and nearshore currents that are generated by waves in breaker zones. However, on-site observations have shown that there also exist strong flows with long periods of several days. As these long-period flows have a high velocity even at deep water levels outside breaker zones. They are thought to play an important role in the offshore drift-sand phenomenon and in the convection and diffusion of floating larvae of marine organisms .Through analysis of observation date on wind velocity and flow velocity recorded around Tomakomai Harbor, the temporal and spatial characteristics of long-period velocity fluctuations of these flows were clarified. We confirmed the existence of and clarified the characteristics of long-period flow velocity fluctuations around Tomakomai Harbor that have a period of 3~4days and propagate in a westerly direction at a phase velocity of approximately 2.0km/h. These long-period flow velocity fluctuations can be estimated by the storm surge formula that assumes wind stress to be the external force and Coriolis force to be the restoring force.


harbor; Tomakomai Harbor; long period flow; velocity; velocity fluctuation

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