Measuring precise sea level from a buoy using the global positioning system

Abstract

High‐accuracy sea surface positioning is required for sea floor geodesy, satellite altimeter verification, and the study of sea level. An experiment to study the feasibility of using the Global Positioning System (GPS) for accurate sea surface positioning was conducted. A GPS‐equipped buoy (floater) was deployed off the Scripps pier at La Jolla, California during December 13–15, 1989. Two reference GPS receivers were placed on land, one within ∼100 m of the floater, and the other about 80 km inland at the laser ranging site on Monument Peak. The position of the floater was determined relative to the land‐fixed receivers using: (a) kinematic GPS processing software developed at the National Geodetic Survey (NGS), and (b) the Jet Propulsion Laboratory's GIPSY (GPS Inferred Positioning SYstem) software. Sea level and ocean wave spectra were calculated from GPS measurements. These results were compared to measurements made with a NOAA tide gauge and a ParosTM pressure transducer (PPT). GPS sea level for the short 100‐m baseline agrees with the PPT sea level at the 1‐cm level and has an rms variation of 5 mm over a period of 4 hours. Agreement between results with the two independent GPS analyses is on the order of a few millimeters. Processing of the longer Monument Peak ‐ floater baseline is in progress and will require orbit adjustments and tropospheric modeling to obtain results comparable to the short baseline.

Kinematic GPS Precise Point Positioning for Sea Level Monitoring with GPS Buoy

“…Buoys equipped with GPS receivers have been used to measure water levels, atmospheric parameter and other physical conditions in sea, river or lake for the purposes of navigation, tide correction, the altimeter range calibration, ocean environment and pollution monitoring, flood control, and fisheries (Rocken et al 1990, Key et al 1998, Moore et al 2000. For high positioning accuracy applications, the relative positioning RTK technique is widely adopted in most of GPS buoy positioning.…”

A first comprehensive evaluation of China’s GNSS-R airborne campaign: part II—river remote sensing

“…3), and a commercial GPS receiver received the signal from the buoy antenna. Three receivers (two reference stations and one buoy) of the network provided a reference centimeter precision differential height of the surface of the Yellow River by GPS dual-frequency differential positioning method [25], with which the GNSS-R altimetry results from direct and reflected GNSS samples would be compared. Three receivers (two reference stations and one station on the plane) also supplied the decimeter precision differential altitude and position of the plane using kinematic processing.…”

Ocean surface monitoring based on GPS kinematic positioning

“…Not only does GPS supply position for ocean navigation but also other related information because of its high precision kinematic positioning mode. Over the past decades, GPS buoy has been used to measure sea level, sea wave, ocean tide, atmospheric parameter and other physical conditions together with other sensors to serve as offshore wave, tsunami, tide observation [2,6,13,17,18] , altimeter range measurements calibration and some other ocean surface monitoring system [8,14,16,19] . As an efficient way to obtain the position, there are many kinds of GPS kinematic positioning methods, such as the conventional GPS RTK, network GPS and precise point positioning techniques.…”

“…As an efficient way to obtain the position, there are many kinds of GPS kinematic positioning methods, such as the conventional GPS RTK, network GPS and precise point positioning techniques. The conventional GPS RTK technique has been widely adopted in most of GPS buoy positioning when the baseline is not far away off the shore [1,19] . GPS network RTK can be extended to longer baseline but its infrastructure is hard to set up for ocean positioning application [11,21] .…”