TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 53 (No. 2), pp. 143-159, 1997

Characteristics of Internal Tides in the Upper Layer of Sagami Bay

Yujiro Kitade and Masaji Matsuyama

Department of Ocean Sciences, Tokyo University of Fisheries, 4-5-7, Konan, Minato-ku, Tokyo 108, Japan

(Received 18 March 1996; in revised form 26 August 1996; accepted 28 August 1996)

Abstract: Internal tides in the upper layer of Sagami Bay were investigated by long-term temperature observations at seven stations during the period from summer to fall in 1991. Statistical analysis of the data shows the following features of internal tides. The temperature fluctuations due to the semidiurnal internal tides are predominant in the bay throughout the observational period, but the amplitudes and phases are considerably different among the stations. The phases at each station shift with the variations of the basic density field as well. Amplitudes of the diurnal internal tides are nearly the same along the bay coast, and phases are mostly independent of the variation of the basic density field. In order to explain these features of internal tides in the bay, numerical experiments using a two-layer model were performed. The results showed that the semidiurnal and diurnal internal tides are generated at the northern part of the Izu Ridge and south of the Boso Peninsula. The semidiurnal internal tides generated are propagated into Sagami Bay with characteristics of Poincaré and Kelvin modes, and they are reflected at the bay head and interfere with the incident internal tides. Phase relations of the semidiurnal internal tides observed in the bay can be well explained as an interference of the internal tide. The diurnal internal tide in Sagami Bay is generated south of the Boso Peninsula, and propagated into the bay trapping along the coast. Characteristics of the diurnal internal tides observed in the bay can be explained as internal Kelvin waves.

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