Ionospheric Scintillation Induced by Hot Flow Anomalies via Particle Precipitation

Ionospheric scintillation disrupts trans‐ionospheric radio signals and represents significant challenges for critical communication and navigation systems. Here we document that hot flow anomalies (HFAs), transient disturbances formed near Earth's bow shock, can contribute to scintillation near the cusp. We used coordinated multi‐instrument observations including GNSS receivers, SuperDARN, AMPERE, DMSP/SSUSI, MMS to link an upstream HFA to the scintillation in the polar ionosphere. During 10:47–10:57 UT on 19 November 2015, enhanced phase scintillation was observed, along with a convection vortex, enhanced field‐aligned currents (FACs) and nearby particle precipitation. An HFA and associated high‐speed jets (HSJs) were observed in the corresponding magnetic local time (MLT) region of the magnetosheath. Our analysis indicates that the HFA disturbs the magnetopause and enhances the FACs, causing the localized ionospheric density gradient instability, thereby triggering the ionospheric scintillation. These results show that the particle precipitation caused by HFAs can strongly affect the cusp plasma and trigger significant phase scintillation. Our results provided direct observational evidence that HFAs are a contributing source of polar space‐weather impacts on GNSS and radio systems.