Theory and applications of using GPS equipped buoys for the accurate measurement of sea level.

摘要

In this thesis, the theory and techniques for the accurate location of a water-borne platform using the Global Positioning System (GPS) are investigated. The objective of this work is twofold: (1) to develop a kinematic precise point positioning algorithm that will provide velocities with centimeter per second accuracy using only single-frequency GPS data and, (2) to demonstrate that a low-cost, wave-rider style buoy, equipped with a dual frequency GPS receiver, can be used to accurately measure the sea surface height. The former objective will be applied to the Fast Pegasus experiments and the later objective will be applied to the Harvest Geoid experiment.;A precise point positioning algorithm is derived that uses a filter/smoother to estimate the state and biases of a moving platform. Results using data from the latest Fast Pegasus experiment indicate that on average the algorithm has positional errors less than 1 m with velocity errors less than 1 cm/s. Therefore, the precise point positioning algorithm is well suited for the Fast Pegasus experiments.;The three goals of the Harvest Geoid experiment were to demonstrate that a wave-rider style buoy could be used: (1) to calibrate the TOPEX/POSEIDON satellite altimeter, (2) to generate a two dimensional sea surface map, and (3) to measure wave height statistics. The buoy measured sea surface heights never differed more than 1.5 cm from the tide gauge measured sea surface heights. In addition, the sea surface map generated by the buoy had 2.4 cm rms difference when compared to the Ohio State University Mean Sea Surface of 1995. The results from this experiment indicate that a low-cost wave-rider style buoy is very capable of accurately measuring sea surface heights.