Extreme Wave Analysis Using Satellite Data

摘要

Suitable satellite coverage of the coastal waters of the UK now span a period of almost 10 years. The recovery of wave heights from satellite observations provides another source of wave climate information for design. However, satellite observations are only accurate in locations greater than approximately 10km from the coast. To be of direct use to coastal engineers these observations must be transformed to shallow water. This can be achieved with numerical wave transformation models that are now available. In this study we have demonstrated this procedure using a spectral refraction model. In situ measurements have been used to investigate the accuracy of satellite-derived wave conditions through a comparison of predicted extreme wave heights. Agreement to within 0.3m up to a return period of 50 years has been found. A wave transformation model was used to transform the satellite-derived offshore wave conditions to inshore locations at which in situ measurements were available. The wave model was validated by transforming offshore in situ measurements to the inshore measurement sites and comparing measurements and predictions. The results of this study are encouraging, but need to be qualified. First, the measurements have been obtained over relatively short periods and theerefore the computed extreme values have a commensurate uncertainty associated with them. Secondly, if relying on satellite-derived results alone some additional knowledge about the wave directionality would be required to perform spectral wave transformation.