A System for Estimating Wave Climate and Wave Extremes Based on 20-Year Wave Hindcast and Its Verification at the Measurement Stations around Japanese Coasts

A long-term wave hindcast system which consists of the ECMWF wind data sets over a period of 20 years from 1979 to 1998 and a shallow water wave model based on backward ray tracing is applied to the estimation of year-long waves at each of almost all measurement stations deployed around the coasts of Japan. Comparison between 2–3 hourly measurement and hindcast is made for a time series of waves, wave climate parameters of each month or over the whole period, their climatic change and extreme wave height. One main finding is that the system is very useful not only for a proper evaluation of the wave climate and its interannual change but also for a first guess of the return wave height with confidence interval at any coastal location around Japan directly facing the open sea, particularly on the Japan Sea coasts.