Near-real-time ionospheric monitoring across the Ring of Fire

Acoustic-gravity waves (AGW) produced by earth-based natural hazards, anthropogenic events, or space-based events propagate into the ionosphere and cause anomalous waveform disturbances that can be measured with Global Navigation Satellite System (GNSS) total electron content (TEC) measurements [2][3]. With the launch of the Jet Propulsion Laboratory’s GUARDIAN system (https://guardian.jpl.nasa.gov) [1] on September 15, 2022, we now have near immediate access to filtered slant TEC observations. Currently, TEC measurements are computed for more than 90 GNSS ground stations that monitor the four main GNSS constellations (GPS, Galileo, BDS, and GLONASS). This system supports the development of near-real-time (NRT) ionospheric monitoring of potential disturbances due to natural or anthropogenic events on Earth. Previous research has shown the success of implementing an LSTM-based algorithm to detect a local AGW disturbances in the ionosphere ten minutes after an earthquake event. This research expands the previous case study to GNSS stations distributed around the Pacific Ring of Fire, searching across a six-month time period 10-01-2023 to 04-15-2024. The challenges are significant as each region across the area of study requires a local “normal” from which anomalous behavior will be assessed. This research shows how the establishment of these regions impacts both monitoring efforts and computational loads. Events during this time period of interest for AGW detection include the 2023-12-02 Mw 7.6 earthquake off Gamut, Philippines, the 01-01-2024 Mw 7.5 earthquake at Noto Peninsula, Japan and resulting tsunami, and the 04-08-2024 solar eclipse. To our knowledge this will be the first experiment showing the feasibility of worldwide ionospheric near-real-time monitoring with GNSS.

References
[1] Martire, L., Krishnamoorthy, S., Vergados, P. et al. The GUARDIAN system-a GNSS upper atmospheric real-time disaster information and alert network. GPS Solut 27, 32 (2023). https://doi.org/10.1007/s10291-022-01365-6
[2] Kaladze, T. D., Pokhotelov, O. A., Shah, H. A., Khan, M. I., & Stenflo, L. (2008). Acoustic-gravity waves in the Earth’s ionosphere. Journal of Atmospheric and Solar-Terrestrial Physics, 70(13), 1607–1616. https://doi.org/10.1016/j.jastp.2008.06.009
[3] Mannucci, A. J., Wilson, B. D., Yuan, D. N., Ho, C. H., Lindqwister, U. J., & Runge, T. F. (1998). A global mapping technique for GPS-derived ionospheric total electron content measurements. Radio Science, 33(3), 565–582. https://doi.org/10.1029/97RS02707