Impacts of Spatially Varying Eddy Diffusion Coefficient in the Lower Thermosphere on the Ionosphere and Thermosphere using GITM

Abstract:

Eddy Diffusion Coefficient (EDC) is used to parameterize the effect of gravity waves in the mesosphere and lower thermosphere (MLT). Gravity waves propagate up from the lower atmosphere into the MLT region resulting in turbulent mixing, composition change, momentum and heat deposition. Because gravity waves span a large temporal and spatial spectrum, estimation of this macroscopic parameter remains elusive. In this study, we employ a 1D transport model that solves for EDC using CO2 densities from SABER and wind velocities from HWM in the MLT. We use this model to calculate EDC over the whole globe to understand the spatial distribution of the gravity wave activity. Spatial distribution of EDC is then used in the Global Ionosphere and Thermosphere Model (GITM) at the lower boundary (~97 km) to understand the effect on the composition, dynamics and temperature of the middle-upper thermosphere and ionosphere.