SEA-LEVEL VARIATIONS WITH A SEVERAL-DAY PERIOD ALONG THE SOUTHWESTERN JAPAN SEA COAST

Daily mean sea-level data obtained along the southwestern Japan Sea coast (the San In coast of Japan and the east coast of Korea) are analysed using a spectral analysis technique. It is found that a prominent peak period of sea-level variations exists at 3-5 days from January to April. These sea-level variations disappear from May to August. The remaining season, from September to December, has a broad peak at a period of 3-10 days. These sea-level variations are highly coherent with the wind variations. The wind-induced sea-level variations in the frequency band from a 2.5- to 6-day period propagate with the coast to the right-hand side and were non-dispersive. The progressive waves along the San In coast and the east coast of Korea propagate independently. The wave along the San In coast can be explained by a first mode shelf wave and begins to propagate from the Tsushima Straits. We cannot specify the type of wave along the east coast of Korea, since it propagates at a speed intermediate between that of a shelf wave and an external Kelvin wave.