Observations of High‐Resolution Two‐Dimensional Ionospheric Flow Dynamics Associated With Poleward Boundary Intensifications

Abstract Poleward boundary intensifications (PBIs) are one of the most common auroral disturbances and have been shown to play a key role in substorm dynamics. PBIs are commonly interpreted as the ionospheric signature of magnetotail reconnection, providing insight into X‐line evolution. While PBIs have been linked to ionospheric flow channels using line‐of‐sight observations, their two‐dimensional flow dynamics remain poorly understood. Using coordinated THEMIS All‐Sky Imager and SuperDARN observations, we present high‐resolution two‐dimension flows derived by the spherical elementary current systems (SECS) method in association with PBI morphology. AMPERE magnetic perturbation data are presented for one event to analyze the current system associated with a dawn‐cell PBI. Ionospheric flow channel observations are used to infer plasma inflow in the magnetotail, and our results show they play a determining role in PBI morphology, including spatial extent, number, and propagation. These results suggest that inflow properties strongly influence X‐line dynamics.