Neutral Wind Estimations From Different Methods and Impacts of Neutral Dynamics on the M-I-T Coupled System

An accurate description of neutral winds in the thermosphere is essential to understand the upper atmosphere variations. Although the vertical winds are typically small compared with the horizontal winds, they can be non-zero under certain conditions and the influence ofthe vertical winds on the thermosphere can be substantial due to the large gradient of neutral density in the vertical direction. Meanwhile, the horizontal winds can strongly contribute to the high-latitude electrodynamics and possibly influence the magnetosphere through neutral wind dynamo. Typically, the vertical neutral winds are estimated in two different ways: 1) calculation from the vertical momentum equation in non-hydrostatic models; 2) estimation from the divergence of horizontal winds with certain assumptions. The second method has been widely used in both hydrostatic simulations and Fabry Perot interferometers (FPIs) observations. A theoretical storm event has been utilized to examine the similarity and difference between vertical wind estimations from those two methods in both quiet and storm times using the non-hydrostatic global ionosphere-thermosphere model (GITM). The physical driver and the consequence on neutral density related to the vertical wind difference have been examined as well. Additionally, the impacts of the neutral wind-driven Pedersen & Hall currents on the high-latitude electrodynamics and M-I-T coupling will be examined using an electrodynamics solver. The contribution of asymmetric neutral wind dynamics to the inter-hemispheric asymmetry in the M-I-T system will be investigated as well.