Western Mediterranean altimetry and gravity covariance study for DOT estimation through MIMOS

The advent of SWOT mission data in combination with the recent altimetry satellites (CryoSat-2, SARAL-AltiKa, Sentinel-3A, Sentinel-3B) provide additional value in regional Dynamic Ocean Topography (DOT) estimation both in the resolution and the accuracy of the final product. The near-real-time records support the phase of the operational altime-try. Two areas in the Western Mediterranean were chosen in order to study the signal and error covariance of each altimetric product from 2017 to 2024. The repeated altimetric tracks were used for the spectral estimation of the signal and error Power Spectral Density (PSD) and covariance. Various covariance models (exponential, Gaussian, ARMA) were tested to fit the data-driven estimation. A similar computation scheme was tested for ma-rine gravity data using simulated repeated fields. The final analytic gravity covariance from the periodogram PSD approach was tested against the fitted empirical one. Finally, gravity and altimetry PSD information is used in the DOT estimation through a tailored Multiple-Input-Multiple-Output-System (MIMOS).