Algorithms for Computation of Water Level Elevation at a Fixed Location from the Water Level Elevations at a Moving Platform.

Abstract : This document provides analytical algorithms for computation of water level elevation time series at a fixed location from water level measurements made on a moving a ocean platform. The algorithms are based on geostatistical techniques, including kriging methods and conditional simulation. Wave or water elevation time histories are usually measured from a fixed reference location. Wave elevation measurements made using a wave measurement attached to a floating ocean platform need to be corrected for the motions of the platform. Most computer simulation programs, including the conditional wave model require wave input for a fixed reference location. The report presents the two basic methods (kriging and conditional simulation), develops a rapid procedure for computing the wave elevation covariance matrix for both methods, and concludes that the kriging method is the better choice. Keywords: Ocean wave kinematics; Statistical analysis estimates; Bessel functions; Fast fourier transforms; Kriging procedures; Directional wave spectra. (edc)