Numerical study of sources of baroclinic tides in Gaoping Submarine Canyon, southwestern Taiwan

The Gaoping Submarine Canyon (GPSC) is a narrow (maximum width of 8 km) and steep (~0.03) canyon locates off southwestern Taiwan. Previous observations indicate depth integrated baroclinic tide energy (~14 kW/m) was strong with complicated generating mechanisms in the GPSC. A hydrostatic, three-dimensional model with two different domains, with or without the Luzon Strait (LS), and two corresponding horizontal resolutions is adopted to investigate sources of baroclinic tides in the GPSC. The initial temperature and salinity fields of the two domains are vertically stratified but horizontal homogeneous. The model is driven by tidal sea level variations calculated from TWTIDE08 at open boundaries. The analyses of large-domain/coarse-grid and small-domain/fine-grid simulations suggest that most of the baroclinic tide energy in GPSC originates remotely from the two meridional ridges in the LS. The semidiurnal M2 tide is the dominant source of the baroclinic tide energy. When the baroclinic tides from LS hit the steep shelf slope in the northern South China Sea, part of the reflected baroclinic energy could propagate into the GPSC. The local baroclinic tide generation becomes effective when the remote baroclinic tides propagate from deep region (>1000 m) towards the head of the GPSC.