A tropical cyclone model is developed for use in both hindcast and forecast applications. It is based on the work of Bretschneider1 with the following modifications:
Navigation of the model along a storm track to generate a time history of wind and wave conditions.
Computation of wave height inside the radius of maximum winds.
Application of a shoaling correction to wave heights generated at shallow water sites.
The model's reliability is tested by hindcasting wind and wave conditions at the locations of environmental buoys deployed in the Gulf of Mexico during Hurricanes Anita, Babe, and Eloise. These hindcast data are compared to measured data recorded at the buoys during the passage of the three hurricanes. The comparisons reveal close agreement between the hindcast and measured data.
A forecast program is then developed in which the model is used to provide numerical guidance to meteorologists preparing wind and wave forecasts under hurricane conditions.
In recent years there have been numerous successful attempts at modeling hurricane wind and wave fields. 2,3,4,5These models have been applied to historical storms (hindcasting) to generate the extreme wind and wave statistics needed for platform and harbor design, risk and venture analysis, and operational planning. Accurate extreme wind and wave statistics have enabled the marine operator to avoid damage due to under design and the extreme expense of over design. In the case of forecasting hurricane wind and wave conditions, the situation has been much different. The present state of the art is such that site-specific wind and wave predictions under hurricane conditions are normally satisfactory at best.
The aim of this project was to adapt a previously developed hurricane wind/wave model (with known error characteristics) for use in providing numerical guidance in the preparation of marine wind and wave forecasts under hurricane conditions. Although the Gulf of Mexico basin is treated exclusively here, the model can be applied at any worldwide location affected by tropical cyclones. The benefits of dependable wind and wave forecast guidance in preparing forecasts for offshore operations (site-specific drilling and construction, ship routing, harbor management, etc.) are numerous.
The hurricane model utilized in this study is based on the work of Bretschneider. l Fifty-one tropical cyclones, covering all possible ranges of latitude, were utilized to develop the hurricane wind and wave parameters. Simple formulae for the determination of wind speed and direction as well as significant (and maximum) wave height and period at any point in the storm circulation were derived. Procedures were also included in the model to allow for correction of the wind and wave fields for storm movement.
These formulae were defined as a function of a few parameters utilized to characterize the intensity, size, and translation of the storm under consideration.