Probability distributions of wave heights in the Lithuanian coast

Abstract

Since discovering that signals of random waves submit to the known laws of probability, this became widely used in engineering and energetics for probability distributions analysis of wave height. From an energetic point of view, it is necessary to know the average wave height in, for example, highly wavy (1% probability), medium wavy (25 % probability) or non-wavy (95% probability) years. Whereas, maximum multi-year value of wave height characteristics is essential for engineering resistant wave energy converters that could withstand severe marine conditions. Average and maximum annual values of wave height data collected from Klaipeda coastal hydrometeorological station are used for this study. Probability distributions of average and maximum wave heights in the Lithuanian coast are analysed in this paper. The best fitting is obtained using HYFRAN and EASY FIT software. Both, a test for independence (Wald- Wolfowitz) and stationarity test (Kendall) are carried out for every time series using HYFRAN software. Maximum likehood method is selected for distribution estimation. Fitting is determined using chi-square test and the best fining is verified with comparison (BIC and AIC) criterion. Fitting for one of the most commonly used distributions in the analysis of wave climate - Rayleigh distribution - cannot be determined with HYFRAN software. For this purpose. EASY FIT software is used additionally. The fit of the distribution is evaluated via the chi-square test similarly. Calculated wave heights based on lognormal probability distribution that fits best according to HYFRAN softvsa-e are similar to those calculated using Rayleigh probability distribution.