Thermospheric Wind Dynamics and Evolution in High Latitudes: Insights from the Momentum Equation for the March 17, 2013, Storm

During geomagnetic storms, magnetospheric energy input into the ionosphere-thermosphere system enhances, driving complex thermospheric wind circulation.This study investigates high-latitude thermospheric wind dynamics and evolution during geomagnetic storms, focusing on momentum transfer from key forces—pressure gradient, viscosity, ion drag, and Coriolis—and the role of advection across altitudes and storm phases. To achieve this, we performed simulation using the Global Ionosphere-Thermosphere Model (GITM) for the March 17, 2013, geomagnetic storm event. The analysis examined thermospheric wind evolution during the onset, main phase, and recovery phase of the storm. Additionally, variations in the forces were studied across four regions: polar cap, auroral oval, and sub-auroral latitude — to examine their latitude dependence relative to the convection pattern. The results showed that viscosity was the dominant driver of thermospheric winds at 355 km (GDC mission’s proposed altitude), exceeding 1 m/s² and peaking above 2 m/s². The pressure gradient force followed, mostly below 1 m/s², while advection was weaker. Ion drag and Coriolis forces had minimal contributions (<0.3 m/s²), with ion drag having a slightly noticeable influence during the early positive ionospheric storm phase (increased electron density) before becoming negligible. At sub-auroral latitudes, viscosity was small compared to higher latitudes due to the smaller gradient in wind velocity. Future investigations will analyze multiple geomagnetic storms to determine whether the observed trend in the case study hold across events and to draw broader conclusions about the relative magnitudes and impacts of force terms across storm phases and altitudes.