A Study on the System for the Estimation of Extreme Waves Using a Stochastic Low Model

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A stochastic low pressure model which reproduces 9 parameters of a low pressure-that is, a center position, central pressure of a low, far field pressure, inclination angle of the long axis of a pressure contour and radii of a low for orthogonal 4 axeson the assumption that the air pressure distribution in a low pressure system is approximated with elliptic distribution is developed. This model is based on the statistical analysis of parametric properties of 718 low pressure systems gathered from weather charts over the Northwestern Pacific Ocean for the past 32 years. The stochastic. low pressure model reproduces the characteristics of mean value and also a standard deviation of a characteristic of actual low pressures.Distribution of extreme value of air pressure and wind speed over the Northwestern Pacific Ocean based on simulated data that combined the stochastic low pressure model, elliptic air pressure distribution model and gradient wind model correspond with the extreme value based on ECMWF (European Center for Medium-Range Weather Forecasts) air pressure and wind analysis data.Return wave height at Japanese wave observation points along the Japan Sea coast and the Pacific Ocean coast estimated by the "System for the Estimation of Extreme Waves using a Stochastic Low Model" consists of the stochastic low pressure models a wind estimation model, wave hindcast model at a single point with high topographical resolution in shallow water and extreme value analysis model correspond comparatively with the return wave height estimated by the observation data. Return wave height estimated on the basis of the system that uses a wave hindcast model over grid points in deep water coincides to return wave height based on the point model in shallow water, in cases that are not affected by the sheltering effects of the land and that face the open sea.