Multi-year sea level estimation at O´Higgins station using GNSS interferometric reflectometry

Multi-year sea level estimation at O´Higgins station using GNSS interferometric reflectometry

Ole Roggenbuck, Axel Rülke, Elke Kühmstedt, Christian Plötz

Bundesamt für Kartographie und Geodäsie, Richard-Strauss-Allee 11, 60598 Frankfurt am Main

Precise knowledge of the local ocean tides is important to correct space geodetic observations for ocean tide loading displacements. In remote areas as Antarctica ocean tide models still suffer from limited coverage of satellite altimetry observations in high latitudes and especially in coastal areas. The coverage of tide gauges is poor in this region and their continues operation is still a challenge due to harsh environmental conditions.

The GNSS interferometric reflectometry (GNSS-R) is a promising method for continues observations of the sea surface heights (SSH) near the coast. In GNSS-R the signal to noise ratio (SNR) is analyzed to obtain the height difference between the GNSS antenna phase center and the reflecting sea surface. The method determines the sea surface height directly in the global reference system.

The German Antarctic Receiving Station (GARS) O’Higgins is located at the northern tip of the Antarctic Peninsula and jointly operated by the German Aerospace Center (DLR) and the German Federal Agency for Cartography and Geodesy (BKG). The radio telescope is used for VLBI observations within the International VLBI Service.

In this study we analysed 1 Hz GNSS observation data from the GNSS marker OHI3 at O’Higgins in order to determine SSH. We analysed several years of data using an inverse modelling approach. We introduce the method and assess their error budget. The GNSS-R results are compared to simultaneous campaign-wise tide gauge observations. The multi-year solution is used to estimate a set of tidal harmonics which is compared to existing ocean tide models.