Abstract
The long period oscillation (LPO) with high amplitude (1m) and period less than 5-minute was observed at Shimohaya Bay in Wakayama Prefecture in a storm. The sea wind gustiness and wave group observed at the offshore area had the nearly same period as the LPO. We had the numerical simulation of the LPO, assuming that the LPO was generated by only groupness effect of breaking waves. The results showed enough intensity of amplifying of long wave by topographic resonance (6-minute long wave was amplified more than 10 times in Shimohaya Bay). However, the high amplified point was not restricted in Shimohaya Bay by the simulation.
