Revisiting studies of the orientation of low-latitude scintillation patterns using a local network of spaced GNSS-based monitors

Low-latitude ionospheric scintillation can be described as the manifestation of fast-moving and time evolving diffraction patterns created by ionospheric irregularities associated with Equatorial Spread F (ESF) (e.g., Basu, S. et al. 1996).

Ionospheric irregularities are commonly assumed to map along geomagnetic field lines, and it has been proposed that the orientation of this scintillation pattern can be determined by a consideration of the projection of the magnetic field vector onto the receiver plane (Kintner et al. 2004).

Kintner et al. (2004) described this orientation using a straightforward projection model. The model was able to represent some of the data tested but was deemed unsatisfactory for nearly two thirds of the dataset. Here, we revisit their work and compare it with experimental data. More specifically, we extend their projection model to the general case, accounting for different projection geometries with respect to the magnetic vector at each ionospheric pierce point (calculated using IGRF-13) and a non-ideal receiver plane.

We apply our approach using measurements made during a week-long campaign in March 2023 at the Jicamarca Radio Observatory in Peru. Measurements were made by five GNSS-based scintillation monitors placed in baselines with lengths ranging from 940m to 6.4km in the magnetic N-S direction and a single baseline 144m long apart in the E-W direction. By performing a correlation analysis on the GNSS signals received by the stations, we could directly measure the orientation of the scintillation pattern. We compare these measurements with the modeled values, finding good agreement between the expected and the measured orientations even among the set that was discounted from the original analysis.