Sea level changes monitoring using GNSS technology – a review of recent efforts

Sea level is traditionally observed with tide gauges (TG). These measurements are relative to the Earth’s crust. To improve the understanding of sea level changes it is necessary to perform measurements with respect to the Earth’s center of mass. This can be done with satellite techniques. Global Navigation Satellite System (GNSS) is a tool that can solves several hundred kilometers vectors with centimeter level of accuracy and can measure point height changes relative to the reference ellipsoid WGS84 which is centred at the actual center of mass of the Earth. Although in the past two decades GNSS were used in almost every field of geodetic measurements, it is still almost not in use in the field of sea level monitoring. Attempts of using GNSS equipped buoys for the determination of precise sea level (at centimeter level) were successful and suggest that GNSS is capable of replacing the conventional tide gauges. A review of recent efforts made on observing sea level variations using data from a GNSS receivers were presented here. Furthermore, presented review resulted in a conclusion that the use of a GNSS based Tide Gauge (GNSSTG) system for the determination of sea level changes is possible, and that its accuracy level (averaged) is equal to a float based tide gauge. More than that, an absolute change of sea level should be easier to be determined using GNSSTG system ISSN: 0001-5113 AADRAY ACTA ADRIAT., 55(2): 145 162, 2014