High-Frequency Sea Level Variations Observed by GPS Buoys Using Precise Point Positioning Technique

Abstract

In this study, sea level variation observed by a 1-Hz Global Positioning System (GPS) buoy system is verified by comparing with tide gauge records and is decomposed to reveal high-frequency signals that cannot be detected from 6-minute tide gauge records. Compared to tide gauges traditionally used to monitor sea level changes and affected by land motion, GPS buoys provide high-frequency geocentric measurements of sea level variations. Data from five GPS buoy campaigns near a tide gauge at Anping, Tainan, Taiwan, were processed using the Precise Point Positioning (PPP) technique with four different satellite orbit products from the International GNSS Service (IGS). The GPS buoy data were also processed by a differential GPS (DGPS) method that needs an additional GPS receiver as a reference station and the accuracy of the solution depends on the baseline length. The computation shows the average Root Mean Square Error (RMSE) difference of the GPS buoy using DGPS and tide gauge records is around 3 -5 cm. When using the aforementioned IGS orbit products for the buoy derived by PPP, its average RMSE differences are 5 -8 cm, 8 -13 cm, decimeter level, and decimeter-meter level, respectively, so the accuracy of the solution derived by PPP highly depends on the accuracy of IGS orbit products. Therefore, the result indicates that the accuracy of a GPS buoy using PPP has the potential to measure the sea surface variations to several cm. Finally, highfrequency sea level signals with periods of a few seconds to a day can be successfully detected in GPS buoy observations using the Ensemble Empirical Mode Decomposition (EMD) method and are identified as waves, meteotsunamis, and tides.

Analysis of floating debris behaviour in the Nakdong River basin of the southern Korean peninsula using satellite location tracking buoys

“…Lee et al, 1997;Hocker and Wardwell, 2001;Yu et al 2002b;Dong et al, 2008;Song and Bae, 2011;Kuo et al, 2012) and rivers (e.g. Earle et al, 2005;Emery et al, 2009;Apel et al, 2012) as they are relatively easy to produce and operate.…”

La mesure du niveau de la mer par bouées GPS

“…Elle reflète dans un seul paramètre le bruit de la série (y compris le mouvement réel de la bouée) et la différence au niveau du référencement absolu. (KUO et al, 2012 ;FUND et al, 2013). Les résultats ne sont pas encore aussi concluants que ceux obtenus avec le traitement différentiel lorsqu'une station de référence proche est disponible.…”

“…La technique GNSS présente l'avantage de fournir des données directement rapportées à un système de référence géocentrique mondial alors Thème 3 -Instrumentation, mesures, imagerie et télédétection que les marégraphes fournissent des mesures du niveau de la mer par rapport à la croûte terrestre. Différentes applications des bouées GPS ont déjà été publiées, telles que l'étalonnage des marégraphes côtiers sur des îles éloignées (WATSON et al, 2008 ;TESTUT et al, 2010 ;MARTÍN-MÍGUEZ et al, 2012 ;FUND et al, 2013) et dans des zones au large (BOUIN et al, 2009 ;BALLU et al, 2010 et al, 2011), en utilisant l'ellipsoïde du système de référence géodésique GRS80. Dans un second temps, les positions des bouées ont été estimées par rapport à cette station ILDX à l'aide du module TRACK de la suite logicielle GAMIT/GLOBK permettant le traitement cinématique en mode différentiel.…”

Experimental assessment of post-processed kinematic Precise Point Positioning method for structural health monitoring

“…PPP has been demonstrated to be a powerful and efficient method for many scientific research and for civilian applications (Li & Zhang 2013), such as crustal deformation monitoring (Savage et al 2004;Hammond & Thatcher 2005;Calais et al 2006;Ohta et al 2008), GPS seismology (Kouba 2003;Avallone et al 2011), earthquake early warning system , GPS buoy (Kuo et al 2012;Fund et al 2013), precise orbit determination of low Earth orbiting satellites (Bock et al 2003) and the precise positioning of mobile objects in land, air and marine (Gao et al 2005;Zhang & Andersen 2006;Geng et al 2010;Alkan & € Ocalan 2013). Kouba (2003) first applied PPP to process the high-rate GPS data for the 2002 Denali Fault earthquake and demonstrated that PPP method using the clock and orbit product of the International Global Navigation Satellite Systems Service (IGS) can be used for detecting seismic waves and satisfy the requirement of the GPS seismology.…”