Improving the Coastal Mean Dynamic Topography by Combining the Geodetic Approach from GNSS at Tide Gauges and Satellite Altimetry

The ocean mean dynamic topography (MDT) is the surface representation of ocean circulation. It may be determined by the ocean approach which involves temporal averaging of numerical ocean circulation models, or by the geodetic approach, where it is derived using the ellipsoidal height of the mean sea level above the geoid. The ellipsoidal height of the mean sea surface might be estimated at the coast by connecting the tide gauge datum to a geocentric reference frame through co-located GNSS measurements.

In this study we present a close evaluation of a new set of 302 GNSS-connected tide gauges used to compute coastal MDT values and a novel approach to improve the coastal mean dynamic topography based on both satellite altimetry and tide gauge data.

This approach was evaluated at the Northeast Atlantic coast where the network of ellipsoidal heights at tide gauges is dense. An improvement was observed by comparing the newly derived coastal MDT with the conventional satellite only MDT models.