Specifying the Offshore Environment

Forristall, George Z.; ,

Specifying the Offshore Environment

by George Z. Forristall, Shell Development Co, Houston, United States,

Document Type: Proceeding Paper

Part of: Civil Engineering in the Oceans V

Abstract:

Hindcasting has become a generally accepted method of producing long time series of environmental events from which environmental design criteria can be developed. The need for reliable hindcasts has stimulated research into both descriptive and dynamic models of severe storms and the response of the ocean to those storms. Hindcast models can also usefully describe features of the mesoscale ocean circulation such as the Loop Current and its eddies in the Gulf of Mexico. In this review, we examine the hindcast philosophy with illustrations of models for winds, waves, and currents. Areas needing further research are highlighted. These areas include low frequency wind spectra, frictional dissipation of waves in shallow water, hurricane driven currents over the shelf break, and extremes in the mesoscale ocean circulation. The response of a structure generally depends on some combination of environmental criteria. Joint distributions of the oceanographic parameters can be developed from hindcasts, but it is difficult to determine the relative importance of the parameters in generating the response. The most direct way to develop combined criteria is through integration of their effects on sample structures. A number of groups have now developed implementations of this concept, which fortunately seem to give similar results.

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