Global Navigation Satellite Systems Observations of the Ionosphere during Strong Thermal Emission Velocity Enhancement

We record the first collocant observations of GNSS total electron content (TEC), scintillation, and precise point positioning (PPP) variation associated with Strong Thermal Emission Velocity Enhancement (STEVE) emissions, a recently-discovered, aurora-like arc characterized by a mauve glow, enhanced temperatures, and enhanced ion flow speed. We used optical imaging data from the Time History of Events and Macroscale Interactions during Substorms all-sky imagers to determine the spatial and temporal dynamics during the STEVE event on March 26th, 2008. Additionally, we used GNSS receiver data from the University Navstar Consortium to find TEC, scintillation, and PPP during STEVE. Although the theory of ion recombination suggests that TEC decreases during STEVE, interestingly, we found an unexpected enhancement of TEC associated with STEVE. TEC enhancement closely followed the path of STEVE longitudinally and was localized to STEVE. PPP exhibited enhanced variance locally around STEVE, indicating that the GNSS positioning error increased significantly. We suggest that the TEC enhancement during STEVE creates local TEC structures in the ionosphere that degrade GNSS signals and PPP performance. The TEC enhancement is likely created by energetic particle precipitation and Pedersen drift across STEVE. These results quantify STEVE's impact on ionospheric dynamics and GNSS navigation for the first time.