Extreme, transient bursts of energy in the auroral ionosphere. I. Predictive radar tracking
Abstract
Three-metre Farley-Buneman irregularities observed by the \textsc{icebear} VHF radar organize into clusters whose apparent motion follows the electric field mapped from the magnetosphere. We track these clusters automatically: each is bounded by an α-shape at every time step, consecutive frames are associated by an optimal assignment combining shape overlap with a predicted displacement. Births, deaths, splits, and mergers are monitored, and each trajectory is reduced to per-segment velocities by piecewise linear regression. Tracked speeds are validated against in-situ ion drifts measured by DMSP F16 during two conjunctions in May 2021. Across four years of disturbed conditions, the speed distribution of 74,517 tracked clusters agrees with Swarm A cross-track ion drifts to within a factor of two in probability density for all speeds between 300 and 4000 m/s, and the radar-tracked speed distribution continues as a power law well beyond the noise limit imposed on Swarm by spacecraft attitude jitter. Binning by geomagnetic activity yields a parameterization of the field dispersion conditional on threshold exceedance, σ2 = 3.68 × 105 (SME/100 nT)0.353~m2 s−2, equivalent to 30 to 60 mV/m across the observed activity range, which supplies the amplitude statistics entering the variance term of height-integrated Joule dissipation. During the 10 May 2024 super-storm, on closed field lines equatorward of the dayside cusp, we retrieved an upper-tail sample of this distribution, finding a cluster moving at 11,240±660 m/s and implying a field of approximately 560 mV/m. Together with the unstable fraction of a space weather model's grid volume, our parameterization can in future close the sub-grid contribution to the storm-time heating budget in the auroral ionosphere.
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BibTeX
@misc{ivarsen2026extreme,
title = {{Extreme, transient bursts of energy in the auroral ionosphere. I. Predictive radar tracking}},
author = {Magnus F Ivarsen and Jean-Pierre St-Maurice and Devin R Huyghebaert and Yukinaga Miyashita and Saif Marei and Jordan Cho and Mahith Madhanakumar and Megan Gillies and Dan Billett and Glenn C Hussey},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2605.31046},
eprint = {2605.31046},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.31046},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Extreme, transient bursts of energy in the auroral ionosphere. I. Predictive radar tracking
AU - Magnus F Ivarsen
AU - Jean-Pierre St-Maurice
AU - Devin R Huyghebaert
AU - Yukinaga Miyashita
AU - Saif Marei
AU - Jordan Cho
AU - Mahith Madhanakumar
AU - Megan Gillies
AU - Dan Billett
AU - Glenn C Hussey
PY - 2026
DA - 2026/09/11
PB - arXiv
DO - 10.48550/arxiv.2605.31046
UR - https://arxiv.org/abs/2605.31046
AB - Three-metre Farley-Buneman irregularities observed by the \textsc{icebear} VHF radar organize into clusters whose apparent motion follows the electric field mapped from the magnetosphere. We track these clusters automatically: each is bounded by an α-shape at every time step, consecutive frames are associated by an optimal assignment combining shape overlap with a predicted displacement. Births, deaths, splits, and mergers are monitored, and each trajectory is reduced to per-segment velocities by piecewise linear regression. Tracked speeds are validated against in-situ ion drifts measured by DMSP F16 during two conjunctions in May 2021. Across four years of disturbed conditions, the speed distribution of 74,517 tracked clusters agrees with Swarm A cross-track ion drifts to within a factor of two in probability density for all speeds between 300 and 4000 m/s, and the radar-tracked speed distribution continues as a power law well beyond the noise limit imposed on Swarm by spacecraft attitude jitter. Binning by geomagnetic activity yields a parameterization of the field dispersion conditional on threshold exceedance, σ^2 = 3.68 × 10^5 (SME/100 nT)^0.353~m^2 s^−2, equivalent to 30 to 60 mV/m across the observed activity range, which supplies the amplitude statistics entering the variance term of height-integrated Joule dissipation. During the 10 May 2024 super-storm, on closed field lines equatorward of the dayside cusp, we retrieved an upper-tail sample of this distribution, finding a cluster moving at 11,240±660 m/s and implying a field of approximately 560 mV/m. Together with the unstable fraction of a space weather model's grid volume, our parameterization can in future close the sub-grid contribution to the storm-time heating budget in the auroral ionosphere.
ER -