engleski

Availability of the International GNSS Service observables for GNSS performance studies in Croatia

In scientific of space weather effects on GNSS perforomance the existence of large database of archived both space weather and ionospheric indices and raw GNSS observations is fundamental issue. Exploring the GNSS observables is one of the most important ways for identification of GNSS vulnerabilities and development of solutions for their overcoming. While internet offers access to several excellent space weather-related databases, the problem of accessing reliable raw GNSS observables. The International GNSS Service (IGS) has been established in a support of scientific community in order to provide free access to raw GNSS obeservables collected on various reference sites throughout the world. Here an assessment of quality of IGS GNSS observables for GNSS perforomance studies in Croatia and surrounding region (Croatia, northern Italy, Austria, Slovenia, Hungary, Serbia and Bosnia and Herzegovina) is presented. Two quality parameters (full-day coverage as reliability, and number of days with available data as continuity) are defined, and quality assessment conducted for IGS reference stations in the related region for the year 2006. Analysis revealed decreasing of both reliability and continuity of the IGS GNSS raw observables for the region in question. The situation is especially worsened in periods of space weather disturbances, as shown by comparison of time series of IGS GNSS observables quality parameters and space weather indices. Apparently, researchers addressing space weather effects on GNSS perforomance in Croatia and surrounding regions suffer from steadily decreasing access to relevant data. Paper concludes with selection of alternatives, and proposal for orchestrated actions to sustain access to GNSS observables for researchers in Croatia and surrounding region.

IGS stations; GNSS observables; data availability

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