GPS Tides: A Project to Determine Tidal Datums with the Global Positioning System

摘要

The recent development of On-The-Fly ambiguity resolution techniques with GlobalPositioning System (GPS) observations has created a powerful tool for the study of dynamic time series, such as tidal analysis or the study of water level heights. Ten days of data, at a one-second sampling interval, were collected at a station in the open waters of the Bay of Fundy, followed by ten days from an inshore mooring. The buoy data were transmitted in real time to a reference station on shore where antenna heights were computed in real time. Subsequent processing reduced the 1-Hz antenna height series to a 15-minute water surface height series for comparison to two nearby 'conventional' gauges. Mean tide heights computed from the inshore data are all within 1 centimeter. The means, computed from the inshore series, differed by 20 centimeters between the buoy and the 'conventional gauges,' indicating a differential slope between the water surface and the ellipsoid. In addition to the water surface. measurements, about 20 days of GPS data was collected from a static baseline to characterize the performance of the On-The-Fly GPS system, without the influence of a moving platform. This project has demonstrated that the 'GPS buoy' is a viable method of tidal datum determination and it should be possible to use the ellipsoid as the basis for water surface datums. (AN).