Noise Characteristics of Operational Real‐Time High‐Rate GNSS Positions in a Large Aperture Network

• Published in: Journal of geophysical research. Solid earth 2020-07, Vol.125 (7), p.n/a
• Main Authors: Melgar, Diego, Crowell, Brendan W., Melbourne, Timothy I., Szeliga, Walter, Santillan, Marcelo, Scrivner, Craig
• Format: Article
• Language: English
• Subjects: Algorithms; Apertures; Computer simulation; Earthquakes; Geophysics; Global navigation satellite system; GNSS; Monitoring; Navigation; Navigation satellites; Navigation systems; Navigational satellites; Noise; Noise generation; Outliers (statistics); Quality control; Seismic activity; seismology; Waveforms
• ISSN: 2169-9313; 2169-9356
• DOI: 10.1029/2019JB019197

Large earthquakes are difficult to model in real‐time with traditional inertial seismic measurements. Several algorithms that leverage high‐rate real‐time Global Navigation Satellite Systems (HR‐GNSS) positions have been proposed, and it has been shown that they can supplement the earthquake monitoring effort. However, analyses of the long‐term noise behavior of high‐rate real‐time GNSS positions, which are important to understand how the data can be used operationally by monitoring agencies, have been limited to just a few sites and to short time spans. Here, we show results from an analysis of the noise characteristics of 1 year of positions at 213 GNSS sites spanning a large geographic region from Southern California to Alaska. We characterize the behavior of noise and propose several references noise models which can be used as baselines to compare against as technological improvements allow for higher precision solutions. We also show how to use the reference noise models to generate realistic synthetic noise that can be used in simulations of HR‐GNSS waveforms. We discuss spatiotemporal variations in the noise and their potential sources and significance. We also detail how noise analysis can be used in a dynamic quality control to determine which sites should or should not contribute positions to an earthquake modeling algorithm at a particular moment in time. We posit that while there remain important improvements yet to be made, such as reducing the number of outliers in the time series, the present quality of real‐time HR‐GNSS waveforms is more than sufficient for monitoring large earthquakes. Key Points We study the noise behavior of 213 HR‐GNSS sites from California to Alaska We characterize the spatiotemporal noise behavior and propose reference noise models The present real‐time noise is low enough that GNSS can be used for monitoring earthquakes