Utility and Limitations of Reflected GPS Signals for Local Sea Level Variations Measuring

Abstract:

In this study, an alternative well-known method based on the multipath theory for specular reflections and the use of signal-to-noise ratio (SNR) from a geodetic-quality GPS receiver is demonstrated to determine the local sea level variations. The observations of SNR provide a simple method to extract the frequencies to measure the variations of the sea level. We analyzed 24-hour 1 Hz GPS SNR data for a whole year from two local GPS tide gauge stations, KASH and LNDO, installed at the Kaohsiung and Longdong Port in the southwest and northeast Taiwan, respectively. Daily sea level variations are near to 1.5 m at these two KASH and LNDO sites. The sea level variations from the GPS SNR data are compared with the records from the traditional tide gauges and also with the 8-day sea level GPS positioning results from a buoy instrument setting in the Kaohsiung Port nearby the KASH site, respectively. Precision and accuracy of the sea level variations from GPS SNR data will be assessed. The limitations and prospects of using reflected GPS signals to estimate sea level variations will be also discussed in this study.