Signals from global navigation satellite systems (GNSS) showed scintillation, meaning fluctuations in their phase or strength, in temporal and spatial relation to a single purple STEVE arc over Antarctica, according to the study. About 19 satellites crossed or passed close to the feature's visible appearance.
The event occurred on May 9, 2019, over Dronning Maud Land during what the study described as quiet geomagnetic conditions. Kp was 2-, SYM-H was around -7 nanoteslas, and AE was about 250 nanoteslas during STEVE, after reaching about 400 nanoteslas around 08 UT.
What the receivers recorded
Researchers used high-resolution dual-frequency measurements sampled at 50 hertz by scintillation receivers at Troll and SANAE IV. They turned those measurements into one-second phase and amplitude indices after applying a sixth-order high-pass filter with a 0.1-hertz cutoff to detrend the carrier phase.
At SNA, the noise level for the phase and amplitude indices was around 0.03. Variations exceeded that reference and could reach two times or more above it. Small changes in S4, the study's amplitude-scintillation index, were reported for SNA G08, TRL E31 and TRL R13; the G08 changes appeared only on L1CA and began before the phase and glow-intensity peaks.
The satellite path made a difference
Signal responses varied with crossing geometry. For SNA E18, an almost perpendicular entry coincided with a clear phase-scintillation peak at 23:31 UT on both E1 and E5a. The more tangential E26 case showed above-noise variation from 23:18 UT and two peaks, at 23:31 UT and 23:37 UT.
Across the cases with reported effects, all the GNSS satellites were at elevation angles greater than 40 degrees. Perpendicular crossings showed stronger fluctuations than tangential crossings, while satellites passing the picket fence did not show the variations discussed in the analysis.
A possible change in height
Projection comparisons suggested that the arc's apparent height changed from 230-250 km to 170-200 km over 10 minutes. The comparison used ionospheric pierce points, projected locations where the signal path crossed the ionosphere, and all-sky-imager projections; because the estimate was projection-based, it could reflect spatial structure, temporal evolution or both.
The study also examined an inter-frequency linear combination (IFLC). It showed no visible change in the cases considered, which the authors interpreted as indicating that the increases in the scintillation indices were associated mainly with refractive effects, or changes linked to signal bending. They treated the higher S4 values as suggestive of small-scale plasma structures several hundred metres across and of diffractive effects on GNSS signals.
Why the finding remains tentative
Because only one event was analyzed, the result cannot show how often STEVE is associated with GNSS scintillation or whether stronger events have larger effects. Sparse low-Earth-orbit coverage over Dronning Maud Land also meant that no clean in-situ measurements of ionospheric conditions or drift velocities were available.
The apparent height change was inferred from projections rather than validated by a clean in-situ measurement. The study does not establish that STEVE caused the signal fluctuations, quantify positioning error, signal-integrity degradation or satellite-tracking loss, or identify the dominant instability or directly locate and size the plasma irregularities.
More events are needed to assess the pattern statistically under both quiet and disturbed geomagnetic conditions. Independent in-situ or triangulated optical measurements are also needed to validate the apparent altitude evolution and clarify the roles of candidate instabilities.
Paper data and sources
Original title: A quiet STEVE disturbs navigation satellites' signals in the Antarctic
Authors: Daria Kotova, Luca Spogli, Yaqi Jin, Wojciech Miloch
Journal/Repository: arXiv
Status: Preprint, not yet peer-reviewed
First online: 2026-08-26
DOI: Not available
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