Mapping Mediterranean altimeter data with a multiresolution optimal interpolation algorithm

A multiresolution optimal interpolation scheme is described and used to map the sea level anomaly of the Mediterranean Sea based on TOPEX/Poseidon and ERS-1 data. The principal advantages of the multiresolution scheme are its high computational efficiency, the requirement for explicit statistical models for the oceanographic signal and the measurement errors, and the production of error variances for all estimates at multiple scales. A set of MATLAB-callable routines that implement the multiresolution scheme have been made available via anonymous FTP. The oceanographic signal is here modeled as a stationary 1/km process, where k is the horizontal wavenumber. Measurement noise is modeled as the sum of two separate random processes: a Gaussian white noise process and a correlated process of a low wavenumber representing the uncertainties in the orbital position of the satellite and in the atmospheric load corrections. The efficiency of the multiresolution scheme allowed the testing of more than 16 000 sets of hypothesized statistical prior model parameters to determine the most likely parameters. Mapping results with and without low wavenumber error corrections are presented and compared.