Measuring Coastal Absolute Sea-Level Changes Using GNSS Interferometric Reflectometry

Rising sea levels pose one of the greatest threats to coastal zones. However, sea-level changes near coast, particularly absolute changes, have been less well monitored than those in open ocean. In this study, we aim investigate potential Global Navigation Satellite Systems Interferometric Reflectometry (GNSS-IR) measure and tie on-land (coastal GNSS) offshore (satellite altimetry) observations into same framework. We choose three GNSS stations, each regions subsidence, uplift stable vertical land motions, derive both relative surface heights (SSH) above satellite altimetry reference ellipsoid from 2008 2020. Our results show that accuracy daily mean GNSS-IR is <1.5 cm compared with co-located tide-gauge records, amplitudes annual cycle linear trends estimated measurements data agree within uncertainty. also find de-seasoned de-trended SSH time series collocated are highly correlated statistically well, indicating has monitor provide valuable information for climate studies.