First experience with GNSS data quality monitoring in the distributed EPOS e-infrastructure

The European Plate Observing System (EPOS) is a very large and complex European e-infrastructure that provides pre-operational access to a first set of datasets and services for Solid Earth research. The EPOS-GNSS Data Gateway provides, through an Application Program Interface (API) and a web portal, access to GNSS (Global Navigation Satellite Systems) RINEX data from a distributed infrastructure of data nodes. Currently, ten EPOS-GNSS nodes have been installed, and three of them are still in the pre-operational phase. To monitor the long-term data quality of EPOS-GNSS stations at the nodes level, ROB is developing a new service. The first step of this service is a web portal (www.gnssquality-epos.oma.be) that provides access to data quality metrics of the RINEX data available from the different EPOS-GNSS nodes.

The web portal presents plots of the long-term tracking performance of more than 1000 EPOS-GNSS stations. The plots focus on several data quality metrics such as the number of observed versus expected observations, the number of missing epochs, the number of observed satellites, the number of cycle slips, and multipath values on code observations. These metrics have been computed at the node level using GLASS and Anubis Software (https://gnutsoftware.com/software/anubis). The metrics provide helpful information for node managers or station users to assess the EPOS-GNSS station’s performance and detect potential degradation of the RINEX data quality. The outlook of this work is to investigate the possible usage of data quality metrics to detect data unsuitable for high-precision GNSS analysis for geophysical or meteorological applications. Here, we will present the newly developed web portal, the considered data quality metrics, and some preliminary results of this ongoing work.