Observation of Beat Phenomena of Swells by a Radar in a Coastal Water

Abstract

Wave disasters have been caused repeatedly since long ago by swells which are called Yorimawarinami on the coast of Toyama bay. For examples of the wave disasters, two parsons died and houses, breakwaters, etc. were destroyed in February,2008 and cargo ship REAL drifted and grounded on wave dissipating blocks in October, 2017 in Fushiki-Toyama Port. It became clear by wave generating experiments that wave heights increase twice due to beat phenomena of generated waves in a shallow water, therefore it is considered that the dragging anchors and the grounding on were caused by increasing wave heights due to the beat phenomena of swells with periods of more than 10 seconds in shallow waters.

Then we tried to observe the beat phenomena of swells in shallow water off Ebie using a marine radar and a wave analysis device from December, 2017 to March, 2018. As a result of the observation, we succeeded to catch the beat phenomena of swells by the radar system and we verified that it is possible to observe beat phenomena of swells by radar in a shallow water.