GNSS applications for measuring sea level changes

Kapitel i bok, 2024

Sea level changes are of great interest for society, on local, regional, and global level. During the last decades, the demand for precise and accurate measurement of sea level changes has increased due to ongoing climate change processes and melting of ice sheets and glaciers. Traditionally, sea level has been measured since the 18th century by coastal tide gauges, and since the 1970s by satellite altimetry. Both techniques have their advantages and disadvantages in terms of what exactly is measured and where the measurements relate to. Traditional tide gauges provide relative sea level at the coast, while satellite altimetry gives provides absolute sea level over open ocean. In recent years, also GNSS has proven to be an important source of information for measurements of sea level change. On the one hand, GNSS allows to derive information about the vertical land motion at tide gauges that is necessary to convert the local sea level records to global sea level records. On the other hand, the GNSS technique itself can be used to derive direct information on sea level by exploiting GNSS signals that are reflected off the sea surface and received at coastal GNSS stations. In this chapter we briefly discuss the role of GNSS for measurements of sea level change.