Determination of geopotential value W0L at Polish tide gauges from GNSS data and geoid model

Abstract

Results of three campaigns of Baltic Sea Level Project and further studies reveal the GPS and spirit levelling data possibly contain errors which affect SST and W_{0}^{L} computations. For that reason, the old data were revised and additionally, in spring 2015, the new GNNS campaign was carried out at tide gauges in Swinoujscie, Ustka and Wladyslawowo. The study concerns computation of the local average geopotential value W_{0}^{L} using water level data at the three tide gauges, geoid undulations from a global geopotential model EGM2008 and ellipsoidal heights from GNSS observations, which were obtained using revised data from three campaigns of Baltic Sea Level Project and from the new campaign conducted in 2015. Results obtained indicate that the best estimation of W_{0}^{L} was achieved from the campaign carried out in 2015, where the mean value of W_{0}^{L} calculated for three investigated tide gauge stations is equal to 62636857.45 m2 s−2.