Contribution of satellite data to meteo-oceanic site characterization: A case study

A good knowledge of local sea-state climates is a key factor in the design of offshore structures, the conducting of marine operations and the optimization of shipping routes. In the domain of developing operational site climatologies, one often has to face the problems linked with commonly available information: lack of field measurements, inaccuracy of ship observations, coarse grids and large uncertainties of an atlas, delays and costs of obtaining complete hindcast data. Fortunately, satellite measurements have recently enabled the introduction of dramatic new methods for the derivation of the marine environment: radars borne by GEOSAT, ERS1, or TOPEX now provide reliable world-wide and all-weather wind and sea-state data. Within this scope, operational methods for estimating design significant wave heights from satellite data were developed in a French joint industry project. They led, for various test areas, to precision and confidence ranges similar to those of field measurements. Industrial use of these methods for design sea-state parameters evaluation, corresponding to several planned project lives, is reported in the case of a coastal pipeline layout operation, where classical environmental information was lacking. It is shown that use of satellite data can meet operational short delays and cost-effectiveness requirements. Further research should soon enable improvements and supplement the studies with wave periods and directions via the use of SAR (synthetic aperture radar) wave mode measurements