On February 24, 2008, a twin low pressure system caused very high wave condition on the whole coast of the Japan Sea. The Yorimawari- Nami, peculiar long period swells in the sea, entered Toyama bay and gave unexpected damage to the coastal and port areas. This paper describes the significant waves and spectrum profiles of the swells observed by the coastal wave observation network NOWPHAS. The wave records show that the peak significant wave height and period reached 9.92 m and 16.2 s at Toyama Station on a submarine peninsula in the bay. The shallow water wave simulation using the Boussinesq model tends to amplify the wave energy in some areas due to a peculiar bathymetry with submarine peninsulas and steep slopes in the bay, which is called Aigame in the district.
On February 24, 2008, a twin low pressure system caused very high wave condition on the whole coast of the Japan Sea. The Yorimawari-Nami (Yoshida et al., 1986), sudden peculiar long period swell attack seen in the Toyama-bay coasts in the winter season, leads unexpected damages to the coastal and port areas. The Toyama-bay coastal area has experienced the Yorimawari- Nami attack once or twice every winter season. The Yorimawari-Nami phenomenon is supposed to be caused by winter monsoon in the northern Japan sea area (Nagai, 2002). But the event on February 24, 2008 was the worst one in recent decades. This paper, therefore, describes the significant waves and spectrum profiles of the swells observed by the Japanese coastal wave observation network NOWPHAS.
