Statistics of Hurricane Waves in the Gulf of Mexico

Abstract

This paper reports the results of an extensive study of hurricane-generated waves in the Gulf of Mexico. The study includes hindcasting of historical hurricanes and statistical interpretation of the hindcast wave data to determine maximum wave heights throughout the OCS of the central. and western Gulf of Mexico. Introduction The maximum wave height that reasonably can be expected to affect a structure during its lifetime is one of the more critical factors influencing the design of an offshore structure. By definition, such a wave height is a rare occurrence. The estimation of future occurrences of such waves must reflect, and indeed be derived from, the past history of storm-wave occurrences. Long-term past history of storm-wave occurrences. Long-term historical data bases are required to estimate these rare occurrences with meaningful reliability. Thus, estimating rare future occurrences poses two basic problems:developing a sufficiently long-term historical data base andinterpreting the historical data base to provide reliable estimates of future rare occurrences. The first problem can be solved effectively with hindcasting models. Hindcasting models can be developed and calibrated with contemporary data. These models then are applied with historical storm meteorological data to "re-create" an historical storm-wave data base. In this manner, the need for a long-term historical data base is satisfied by meteorological data.This paper emphasizes the solution of the second problem, which can be stated more concisely: Given an problem, which can be stated more concisely: Given an historical storm-wave data base, what is the most appropriate method for determining the cumulative probability distribution function for the largest waves probability distribution function for the largest waves that will affect a site in tY years? From that distribution function, a variety of wave statistics useful in design studies (e.g., expected maximum wave height in tY years or return-period wave heights) can be determined.This paper describes a study of hurricane-generated waves along the central and western OCS of the Gulf of Mexico. A hurricane climatology characterizing the geographical distribution, wave-generating capability, and frequency of severe hurricanes was derived from historical data. Based on this climatology, a model for estimating the cumulative probability distribution function for the largest wave in tY years from historical wave data was developed. The historical wave data base was generated by hindcasting the more severe historical hurricanes that occurred between 1900–74. Finally, the model was applied with the hindcast data and sample results are presented. Hindcasting Historical Hurricanes The historical wave data base required for this study was developed by hindcasting severe historical hurricanes. The hindcast model used has been described before and will be discussed only briefly here. Hindcast Model The hurricane hindcast model actually consists of two models - a wind-field model and a wave model. The wind-field model is based on a fundamental theoretical description of the relationship between the atmospheric pressure field and winds within a hurricane. The pressure pressure field and winds within a hurricane. The pressure field is described from historical meteorological data. JPT P. 632