An Improved Nonlinear Extraction of Directional Ocean Wave Spectrum from Bistatic HFSWR Using Tikhonov Regularization in Hilbert Scales

The present work proposes the use of a nonlinear inversion technique for the extraction of the directional ocean wave spectrum from bistatic High-Frequency Surface Wave Radar (HFSWR) Doppler data. The extraction method is combined with empirical expressions, solely based on the Doppler data, to retrieve wind speed and direction. Once the initialization parameters have been defined using these empirical expressions, a blind iterative algorithm based on Tikhonov regularization in Hilbert Scales is used to extract the nondirectional spectrum. The extracted spectrum is then used to determine the directional factor, which is assumed to be described by a cosine-power model. The proposed method yields good results with synthetic noise-contaminated HFSWR data with a priori regularization parameters.