TEMPORAL AND SPATIAL VARIATIONS IN A TIDAL FRONT

Temporal and spatial variations in the sharpness and position of a tidal front in Bungo Channel, Japan are investigated using observational data and a variable efficiency model. The front is moved by tidal currents, during the tidal excursion, without changing its sharpness. The front extends far into the Straits, with sharp boundaries on spring tides; it lies adjacent to the Straits, being reduced in its sharpness on neaps. The tidal front is generated in early spring and disappears in early autumn, due mainly to seasonal variation in heat flux through the sea surface. In spite of this seasonal variation, the mean position of the front changes only little from early spring until early autumn. Such temporal and spatial variations in the sharpness and position of the front are reproduced well in output from the variable efficiency model. © 1990.