Quality assessment of the Topo-Iberia CGPS stations and data quality's effects on ionosphere-free phase residuals

Abstract

Abstract GPS data from Topo-Iberia network spanning a period of almost 12 years (2008–2020) have been analyzed. Data quality information for all 26 Topo-Iberia stations is provided for the first time complementing the Spanish Geological Survey’s storage work. Analyses of data based on quality indicators obtained with TEQC have been carried out. Guidelines and data quality information from IGS stations have been taken as quality references. The results show that the Topo-Iberia stations have better or equal quality than more than half of IGS stations. The stations ALJI, EPCU, and TIOU stand out as the worst stations, and on the contrary FUEN, PALM, PILA, and TRIA meet the guidelines to become an IGS station. The relationship between GPS data quality and their GAMIT- and GipsyX-derived ionospheric-free phase residuals has also been studied, and the results reveal an inversely proportional relationship. It has been found that the stations showing an increase in elevation of the horizon line, also show an increase in cycle slips and multipath, are among the poorest quality stations, and among those with the highest root-mean-square of phase residuals. Moreover, the evolution of vegetation around the antenna should be considered as it could cause the progressive loss of quality, not complying with the IGS standards. The quality assessment carried out shows that the Topo-Iberia stations are appropriate for geodetic purposes, but a permanent monitoring would be necessary to avoid the least possible loss of data and quality.