GNSS-Interferometric Reflectometry, spectral artifacts and sea level measurements in the Mediterranean Sea

Abstract

Tidal sea level variations in the Mediterranean basin, although altered and amplified by resonance phenomena in confined sub-basins (e.g., Adriatic Sea), are generally confined within 0.5 meters and exceptionally up to 1.5 meters. Here we explore the possibility to retrieve sea level measurements using data from GNSS antennas on duty for ground motion monitoring and analyze the spectral outcomes of such distinctive measurements. We estimate one year of GNSS data collected on the Mediterranean coasts in order to get reliable sea level data from all public-available data and compare it with collocated tide gauges. A total amount of eleven stations was suitable for interferometric analysis (as for 2021) and all were able to supply centimeter level sea level estimates. The spectra in the tidal frequency windows are remarkably similar to tide gauges data. We find that the O1 and M2 diurnal and semidiurnal tides and MK3, MS4 shallow sea water tides may be disturbed by aliasing effects.