Extreme values of surface wave heights in the northern Adriatic

Abstract

Extreme return values of significant wave heights were calculated using the data of wave heights measured in the open part of the northern Adriatic (platforms PANON and LABIN, lighthouse Sv. Ivan na pučini), by approximating the distribution of monthly extremes by Fisher-Tippet curve (F-T I). Parameters of F-T I distribution of extremes were estimated using three methods: graphic method, method of moments, and maximum likelihood method. Comparison of the results obtained from each method has shown that extreme return values of significant wave heights obtained using the maximum likelihood method best agree with the data of direct instrumental measurements. The greatest significant wave heights are to be expected in the winter period, from December to February. Absolute calculated monthly maximum of a significant wave height occurs in February, being 7.54 m for the return period of 100 years. Major deviations are evident in the summer period (overestimated values), due to a small number of measured data and their dispersion. Extreme expected value of significant wave height in the northern Adriatic for the return period of 100 years is 8.57 m, from which a maximum wave height of about 14 m is estimated, being considered real as regards the maximum measured value of 10.8 m.