On precise GNSS-based sea surface monitoring systems

The paper describes some selected GNSS-based precise technologies developed and used for various maritime applications. Firstly two PVT projects are presented. GNSS-based buoys developed at GFZ Potsdam have been used for calibration of satellite altimeters and for monitoring of sea- and river water levels. Performance and accuracy of PVT can be dramatically degraded by ionospheric threads. Thus, ionospheric mitigation approaches in the PVT solutions are discussed here as well. Finally GNSS remote-sensing technology for monitoring of sea surface roughness and sea level, using reflections of GNSS signals is described. A long-term coastal experiment has been conducted in winter season 2008/09 at Disko Bay with partners (IEEC Barcelona, GFZ Potsdam and ESTEC Nordwijk) as part of the GPS-SIDS project (GPS for Sea Ice and Dry Snow remote sensing). Altimetric and scatterometric applications of ocean reflected signals have been studied to estimate instantaneous sea surface height (SSH) and sea-ice coverage. Reflection analysis revealed ocean tide signatures in SSH estimates and changes in ocean roughness during sea-ice development.