Analysis of water level measurements using GPS

Accurate knowledge about sea level and its change is essential to humanity because a large proportion of the Earth's population lives in coastal regions. This study discusses the existing techniques for sea level measurements, including the use of different types of gauges (e.g., water level gauge or tide gauge, and bottom pressure gauge), as well as GPS and satellite altimetry. The GPS water level measurements from a buoy or a vessel are presented and utilized in this study along with other techniques to collect ellipsoidal, geocentric sea surface height measurements for various studies that help improve our knowledge about sea level and its change.; An operational technique of using GPS water level measurement is proposed in this study. The limitation and an upper bound accuracy of the kinematic (epoch-by-epoch) positioning in terms of baseline length are discussed. A set of GPS data in Lake Erie, including buoy data as well as a local GPS network on land, are used to provide the numerical results.; Three main applications of using the GPS water level measurements are presented in this study. They are integration of various data sources in the coastal, satellite radar calibration, and GPS hydrology. The objective of these applications is to demonstrate the potential of the GPS technique in collecting water level measurements. The use of GPS measurements is also highlighted in connection with the improvement that they may bring to various techniques such as the use of coastal water level gauge and bottom pressure gauge, and satellite altimetry.; The water level gauges are the traditional tools to collect water level data in the coastal areas. A bottom pressure gauge, on the other hand, is deployed away from the shore that senses pressure change in order to infer sea surface variation in terms of depth. Both types of gauges provide only relative measurements, and the land, where they are installed, is subject to the local vertical land movement. In order to take advantage of the large amount of gauge records, a GPS buoy/vessel occupation can be made to link their relative measurements to the global reference frame. This facilitates the integration use of the gauge records to the satellite measurements from altimeters as well as from the GPS technique. (Abstract shortened by UMI.)...