Sea level observations using multi-system GNSS reflectometry

Information on sea level and its changes are important in connection to global climate change processes. For centuries, sea level has been observed with coastal tide gauges and since some decades with satellite altimetry. Furthermore, during recent years the application of Global Navigation Satellite System (GNSS) reflectometry, also known as GNSS-R, for sea level observations has been developed, see e.g., Martin-Neira M. (1993), Lowe et al. (2002), Gleason et al. (2005), Löfgren et al. (2011a,b; 2014), Larson et al. (2013a,b), and Löfgren & Haas (2014). Various methods exist, using ground-based, airborne and space-borne systems, and using different analysis methods. We present results from a dedicated GNSS tide gauge installed at the Onsala Space Observatory at the Swedish west coast. This installation consists of commercially-off-the-shelf GNSS equipment, including geodetic-type choke-ring antennas and geodetic-type receivers and allows for analysis using both phase and Signal-to-Noise Ratio (SNR) data.