Connecting Radio Wave Disruption to “Hot” Charged Particles from Afar

Schematics of a “hot flow anomaly” (HFA) accompanied by high-speed jets (HSJs) forming near the bow shock (BS) and generating transient disturbances in the magneto-sheath (MS; the region between the bow shock and the outer boundary of the magnetosphere, which is called the magnetopause.) These disturbances compress and distort the magnetopause (MP) and drive two localized convection vortices (circular arrows) in the “magnetic cusp” in the polar ionosphere. Field-aligned currents (FACs) are shown as blue magnetic field lines with arrows and connect the disturbed dayside region to the cusp ionosphere and close through the ionospheric current system. The associated particle precipitation (downward spiral arrows) produces structured plasma and sharp density gradients, thereby providing the irregularities responsible for the enhanced phase scintillation. Credit: Zhou et al. [2026], Figure 4 Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: AGU Advances Ionospheric irregularities—small-scale electron density structures in the ionosphere down to meter spatial scales—can cause refractive and diffractive variations (scintillation) to the amplitude and/or phase of a radio signal, and thereby severely disrupt its transmission. Such scintillation can affect satellite navigation and communication systems such as the Global Navigation Satellite System (GNSS). Hot flow anomalies (HFAs) are short-lived flows of hot plasma near the Earth’s bow shock—the region of supersonic plasma shock waves upstream of the Earth’s magnetosphere where the fast solar wind slows down and deflects around the Earth. Zhou et al. [2026] successfully connect the dots between the two using measurements of such HFAs on NASA’s Magnetospheric Multiscale (MMS) satellites and simultaneous measurements of energetic charge particles and ionospheric irregularities from other satellites and from ground GNSS receivers. The authors show a definitive case of direct linkage between an HFA near the bow shock and a localized, enhanced phase scintillation in the polar ionosphere more than 60,000 kilometers away. The HFA and enhanced phase scintillation were associated with a vortex of ion convection and a region of auroral electrons and enhanced electrical current along the magnetic field. The observations suggest that the HFA disturbed the polar ionosphere through a chain of physical processes and created a localized region of ionospheric irregularities, which in turn caused the enhanced phase scintillation and became a source of space weather impact on satellite navigation and communications systems. Citation: Zhao, J.-C., Zhang, Q.-H., Yang, Z.-W., Zhang, D., Oksavik, K., Wang, B.-Y., et al. (2026). Ionospheric scintillation induced by hot flow anomalies via particle precipitation. AGU Advances, 7, e2026AV002548. https://doi.org/10.1029/2026AV002548 —Andrew Yau, Editor, AGU Advances Text © 2026. The authors. CC BY-NC-ND 3.0Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.