Transformation of Significant Wave Heights

Abstract

A formula for transforming significant wave heights of wind seas between locations of differing depths is developed from the concept of the equilibrium range in the spectrum. The transformation is assumed valid for single‐peaked equilibrium wind seas which do not contain swell components. The method does not account for the effects of refraction, diffraction, or situations which may be fetch‐ or duration‐limited, therefore the method should not be applied when these effects may be dominant. The transformation is tested using 198 data pairs which seemed to fit the necessary criteria. The significant wave height at the shallower gage (8 m depth) was predicted using the measured significant wave height at the deeper gage (18 m depth). Comparisons between predicted and measured significant wave heights indicate that the wind sea transformation generally performs better than unrefracted shoaling of significant wave height using linear theory, but that underprediction occurs at longer wave periods.