Crest height statistics of storm waves in deep water

Abstract

This paper presents wave crest statistics for storm waves in deep water obtained from data collected over the last 7 years using wave altimeters mounted on the North Alwyn fixed oil and gas platform in the northern North Sea. The evolution of wave characteristics during the rise, peak and, decay of storms has been examined and it has been found that, as storms develop, there tends to be a focusing of the directional energy as the peak of the storm is approached followed by a directional defocusing as it decays. The effect of this upon the normalized crest elevations has been examined and sample distributions of crest heights taken from the start, peak and end of storms show some differences that are discussed. Three crest elevation probability distribution models based on second-order wave theory have been examined using these data and found to produce quite good predictions of observed crest heights except in the most extreme values.