Observation of internal tides in the East China Sea with an underwater sliding vehicle

Abstract

Detailed structures of internal tides in the East China Sea were observed during autumn from 1986 to 1989, using an underwater sliding vehicle that can measure temperature, conductivity, and depth continuously, sliding up and down along a faired cable. A variety of structures were observed and are classified with internal Froude numbers of the lowest two modes, which depend on the barotropic tidal current velocities and the phase speeds of internal waves (i.e., stratification). In the central East China Sea, the second‐mode waves are most strongly generated at the shelf break and then propagate shoreward onto the East China Sea continental shelf. Since the barotropic tidal current is faster than the phase speed of the second‐mode waves on the shelf, the generation mechanism is consistent with conventional models. On the other hand, in the southern East China Sea the lowest‐mode response is dominant, although the tidal current velocity is slower than the lowest‐mode phase speed. A nonlinear model is proposed for this response.

Variability in nitrogen sources for new production in the vicinity of the shelf edge of the East China Sea in summer

“…These narrow areas are located on either side of the Kuroshio jet, where internal waves were frequently observed (Kuroda and Mitsudera, 1995;Liu et al, 1998;Han et al, 2001;Park et al, 2006). Using a twodimensional analytical model, Baines (1982) predicted that the slope of the continental shelf in the ECS and its adjacent area is the second largest generator of the M 2 internal tides among the major continental shelf slopes in the world's oceans.…”

“…Indeed, a series of studies revealed that internal waves intermittently generated around the shelf break of the ECS and the ridges along the Ryukyu Archipelago could induce enhanced vertical mixing. Consequently, it has been hypothesized that this process may support new production (Kuroda and Mitsudera, 1995;Matsuno et al, 1997Matsuno et al, , 2005Han et al, 2001;Lee et al, 2006;Park et al, 2006). Repeated hydrographic surveys across the shelf break showed that the vertical structure formed by an intensified thermocline and bottom or intermediate mixed layer could change daily (Han et al, 2001).…”

The dynamic responses of flow and near‐bed turbidity to typhoons on the continental shelf of the East China Sea: field observations

“…The NIOs can cause energy and mass exchange between the East China Sea and the Kuroshio region (Kuroda and Mitsudera, 1995), and therefore, they play important roles in ocean dynamics, biological productivity and sedimentary processes along the margin of the continental shelf. However, the more detailed investigation of their structures and processes would require simultaneous observations of temporal evolution of temperature, salinity and velocity fields and so awaits further study.…”

Matched-field processing gain degradation caused by tidal flow over continental shelf bathymetry

“…An extensive literature describing the variety of fluid processes associated with stratified flow over bathymetry exists. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] To the authors' knowledge, the only theoretical or numerical study of acoustic propagation through flow controlled sound-speed fields was done by Sherwin. 16 He presented numerical simulations that related variations in the sound-speed field to tidal flow across a continental shelf break and slope.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Shallow water currents are largely driven by the tide. Consequently, acoustic signals propagating over fixed paths in the continental shelf and slope environment are expected to be temporally variable and exhibit some degree of repeatability in their properties over a tidal cycle.…”