How is GPS (Global Positioning System) used in conjunction with sea level measurements?
Tide gauges are used to measure the sea level with respect to the underlying solid earth. In areas of tectonic motion (continental plate activity), continued glacial isostatic adjustment or serious subsidence due to fluid pumping, changes in sea level are contaminated by vertical land movement signals. If GPS is used to measure the vertical land movement at some point near the tide gauge, then this signal can be removed from the sea level measurements. Removing the land movement signal improves the estimated sea level change. GPS at tide gauges is also used to refer the sea level measurements to a global external reference system, such as the International Terestrial Reference Frame (ITRF). For more information see GPS section under PSMSL’s geophysical signals page or geodesy section of PSMSL’s reading lists.
Tide gauges are used to measure the sea level with respect to the underlying solid earth. In areas of tectonic motion (continental plate activity), continues glacial isostatic adjustment or serious subsidence due to fluid pumping, changes in sea level are contaminated by vertical land movement signals. If GPS is used to measure the vertical land movement at some point near the tide gauge, then this signal can be removed from the sea level measurements. Removing the land movement signal improves the estimated sea level change. GPS at tide gauges is also used to refer the sea level measurements to a global external reference system, such as the International Terestrial Reference Frame (ITRF). For more information see http://www.soest.hawaii.edu/cgps_tg/CGPS@TG_v9.html or http://wwwdev.pol.ac.uk/home_new/psmsl/training/geodesy_etc.
