On the Estimation of Mid-Latitude Ionospheric Irregularity Drifts Using a Local Array of GNSS-Based Scintillation Monitors

Until recently, the ionosphere at mid latitudes was believed to lack conditions favoring the development of scintillation-causing irregularities such as those observed at low and high latitudes. This perception led to reduced deployment of specialized monitors and limited scintillation observations at mid latitudes. The development of low-cost ionospheric scintillation and total electron content (TEC) monitors such as ScintPi (e.g., Gomez Socola and Rodrigues, 2022) have allowed us to carry out observations at mid latitudes and elsewhere that, otherwise, would not be possible due to the relatively high cost of commercial monitors.

Here, we investigate a rare dataset of mid-latitude L-band scintillation observations made by an array of closely-spaced ScintPi monitors. The observations were made at the University of Texas at Dallas (43.2° dip latitude) during the 10-11 October 2024 geomagnetic storm. This event was captured by an array of three ScintPi 4.0 monitors separated by distances of the order of 100 meters. ScintPi 4.0 is the latest version of a series of low-cost scintillation and TEC monitors that combine commercial off-the-shelf (COTS) Global Navigation Satellite System (GNSS) receivers and small computers (Wright et al., 2026a; Wright et al., 2026b). Intense scintillation was observed during this event and persisted for several hours, from local midnight until dawn, and to the south of the observation site.

To study this event, we carried out a spaced-receiver analysis of the fading patterns. Cross-correlations of 50 Hz carrier-to-noise ratio (C/No) measurements were used to estimate diffraction pattern motion. Two spaced receiver models were considered depending on the extent which the patterns are expected to be anisotropic. To quantify the uncertainty in the estimated diffraction pattern parameters, we employed a bootstrap-based resampling methodology.

We then introduce a new inversion approach to relate the observed diffraction pattern velocities to the underlying ionospheric irregularity drift. The method assumes a locally uniform drift field and combines simultaneous observations of GNSS scintillation in a least-squares inversion for the irregularity drift. Preliminary drift estimates indicate predominantly westward and poleward motion during the night of 10 October 2024. The results suggest that the irregularities responded strongly to geomagnetic storm-time electrodynamic forcing.

Overall, these observations demonstrate that low-cost GNSS receiver arrays can provide useful information on storm-time irregularity dynamics at mid-latitudes. The results also extend spaced-receiver analysis theory by introducing a method to directly estimate irregularity drifts from diffraction pattern velocities.
References:

Gomez Socola, J. and F. S. Rodrigues, ScintPi 2.0 and 3.0: low-cost GNSS-based monitors of ionospheric scintillation and total electron content, Earth Planets Space 74, 185, https://doi.org/10.1186/s40623-022-01743-x, 2022.

Wright, I. G., J. Gomez Socola, F. S. Rodrigues, J. F. G. Monico, I. Tsuchiya, A. O. Moraes, and M. A. N. de Azevedo Filho (2026a), ScintPi 4.0: Description and measurements of low latitude phase scintillation, 2026 National Radio Science Meeting, 6 - 9 January 2026, Boulder, CO, USA.

Wright, I. G., J. Gomez Socola, and F. S. Rodrigues (2026b), ScintPi 4.0: A New GNSS-based Low-Cost, Multi-Constellation, Multi-Frequency Ionospheric Scintillation and TEC Monitor for Education, Citizen Science, and Research Initiatives, Under Preparation.

Acknowledgments:
This work was supported by NSF grants AGS- 2122639 and AGS‐2432609 and by an NSF GRFP fellowship.