Analyzing Mechanical Mechanisms in Forming High-Latitude Thermosphere Density and Wind Structures

The high-latitude thermosphere is a region with complex momentum and energy transfer processes associated with its entanglement with the ionosphere and concomitant coupling with the magnetosphere. These complex relationships result in thermospheric density and wind structures that can significantly perturb a spacecraft’s motion in low Earth orbit (LEO) but are not fully captured in empirical and physical models. Recently, Buynovskiy et al. (submitted) applied an ascending-descending accelerometry to CHAMP accelerometer data during quiet geomagnetic activity to disentangle the in-track ambiguity between mass density and winds That work provided a climatological description of acceleration perturbation structures within distinct spatial envelopes on the order of thousands of kilometers in all four quadrants of the northern high-latitudes. These acceleration perturbations are associated with mass density enhancements/depletions, along with in-track (primarily meridional) wind perturbations that have not been considered in accelerometry-derived mass density datasets. Additionally, this combined mass density/in-track wind behavior is not fully captured in the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) V3.0, suggesting the model is insufficiently representing high-latitude behavior. This additional link between mass density and in-track wind perturbations provides an additional parameter to cross reference to explore the effects of momentum and heating sources in the high-latitude thermosphere.

This work investigates processes related to mechanical work, i.e. ion drag force over distance, using TIEGCM to determine the role of this mechanism in producing high-latitude thermosphere density and wind structures. The approach is to emphasize how mechanical work can impact heating/cooling mechanisms, through the manipulation of the governing equations of the ionosphere-thermosphere system within TIEGCM V3.0, to influence the production of wind and density structures that resemble the findings of Buynovskiy et al. (submitted).