16:00 〜 16:15
[AOS14-03] Numerical study of tide-induced deep-ocean mixing near the head of Suruga Trough
キーワード：駿河トラフ、内部潮汐波、地形性捕捉波
Coastal submarine canyons are widely expected to be sites of enhanced mixing which may offer a potential solution to the ‘missing mixing’ problem. In Suruga Bay, mooring observations along the steep submarine canyon (Suruga Trough) show the existence of strong semi-diurnal and diurnal internal tides near the ocean bottom. In this trough, therefore, enhanced turbulent mixing induced by breaking of these internal tides is expected, although details of physical processes that produce strong internal tides have not been discussed yet.
In order to investigate the excitation processes of internal tides in Suruga Trough, we carry out a couple of high-resolution (Δx, Δy = 1/240o) non-hydrostatic three-dimensional numerical experiments incorporating realistic semi-diurnal (M2) and diurnal (K1) tidal forcing, respectively. We first investigate the energetics of M2 internal-tide to show that (1) internal tides generated over Izu Ridge propagate towards Suruga Trough, (2) in which the incident waves interact with the reflected waves from the trough head, and finally (3) the internal tide energy together with its dissipation is intensified. The K1 tidal frequency, on the other hand, is subinertial in this area, so that K1 tidal flow mainly generates coastal trapped waves which propagate cyclonically along the coast of Suruga Bay. It is suggested that these coastal trapped waves induce strong velocity shear near the bottom of the trough causing bottom confined intense mixing.
In order to investigate the excitation processes of internal tides in Suruga Trough, we carry out a couple of high-resolution (Δx, Δy = 1/240o) non-hydrostatic three-dimensional numerical experiments incorporating realistic semi-diurnal (M2) and diurnal (K1) tidal forcing, respectively. We first investigate the energetics of M2 internal-tide to show that (1) internal tides generated over Izu Ridge propagate towards Suruga Trough, (2) in which the incident waves interact with the reflected waves from the trough head, and finally (3) the internal tide energy together with its dissipation is intensified. The K1 tidal frequency, on the other hand, is subinertial in this area, so that K1 tidal flow mainly generates coastal trapped waves which propagate cyclonically along the coast of Suruga Bay. It is suggested that these coastal trapped waves induce strong velocity shear near the bottom of the trough causing bottom confined intense mixing.