F‐Region Neutral Wind Response to Multiscale Geomagnetic Forcing During the 27 March 2014 Substorm Event

Abstract Techniques developed in the past few years enable the derivation of multiscale ion convection and particle precipitation patterns from high‐resolution ground‐based observations, and it has been shown in previous studies that such multiscale geomagnetic forcing can contribute significantly to ionospheric and thermospheric disturbances. In this work, the global ionosphere–thermosphere model (GITM) is utilized to simulate the 27 March 2014 substorm event. Simulations are driven by both the original and spatially smoothed multiscale Super Dual Auroral Radar Network electric potential patterns, and the differences between the two sets of simulations are used to evaluate the effects of mesoscale (<500 km) ion convection. GITM‐simulated neutral winds are compared with scanning Doppler imagers (SDI) wind measurements at Toolik Lake (68.6°N, 149.6°W). Neutral wind variations have been further separated into large‐scale (>500 km) and mesoscale (<500 km) structures. Data‐model comparisons show that, while GITM captures large‐scale wind variations reasonably well, it underestimates the magnitudes of mesoscale winds. Both mesoscale ion convection and precipitation are found to substantially enhance the simulated mesoscale neutral winds. Quantitative analyses at a fixed location and over two vortex regions reveal that F‐region neutral wind variations (at ∼270 km) typically lag mesoscale ion drift enhancements by a few to ∼30 min. The maximum magnitude of mesoscale ion drifts is consistently ∼6 times larger than that of the associated neutral wind changes.