TRACERS Small‐Scale Field‐Aligned Currents and Intense GPS Amplitude and Phase Scintillations in the Nightside Auroral Region

We present conjugate observations of ionospheric small‐scale magnetic perturbations and GPS scintillations from the Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS) and the Canadian High Arctic Ionospheric Network (CHAIN) during a storm‐time substorm on 9 August 2025 in the nightside auroral region. Rotational transverse of up to ∼1,000 nT, associated with filamentary field‐aligned currents (FACs) exceeding 150 on spatial scales of ∼1–16 km, were colocated with extreme, localized auroral scintillations ( 10 rad, 0.3) and ∼10 dB‐Hz intensity reduction. The most intense scintillations lasted ∼1.5 s and coincided with peaks in auroral electrojets, Pi2 pulsations, and enhanced dTEC (∼12 TECU). The sheet‐like morphology and spatiotemporal correlation with auroral electrojets suggest that Farley–Buneman processes likely play a dominant role in scintillation formation, with additional contributions from FAC‐driven and gradient‐drift instabilities.