Influence of multi-scale geomagnetic forcing on the ionosphere-thermosphere system

Abstract:

A systematical study crossing both data analysis and model simulation has been conducted to improve the specification of the high-latitude energy and momentum inputs into the ionosphere-thermosphere (I-T) system at multiple scales. Our results include two parts: large-scale soft particle precipitation and meso-scale electrodynamics. First, the impacts of soft electrons (<1 keV) on the neutral density have been investigated through using a recently developed empirical model for auroral spectrum and high-latitude electric field and variability (ASHLEY). Soft electron precipitations are typically underestimated in general circulation models (GCMs). The electron precipitation from the aurora part of ASHLEY (ASHLEY-A) directly provides the differential energy fluxes in 19 DMSP energy channels relaxing the auroral spectra assumption and improves the specification of soft electron precipitation. The Global Ionosphere-Thermosphere Model (GITM) simulations are compared between cases with different modeling setups. Data-model comparison has been conducted as well to examine the effects of soft electrons on the neutral density. Secondly, the meso-scale magnetosphere forcing including electric field and particle precipitation has been analyzed and implemented into the GITM to assess the relative contributions of meso-scale forcing to the I-T system. Specifically, the high-resolution ion convection and particle precipitation patterns from Super Dual Auroral Radar Network (SuperDARN) and All‐Sky Imager (ASI) observations have been utilized to improve the description of high-latitude forcing, especially at meso-scale. The influence on the Joule heating and I-T response to a geomagnetic storm has been examined. The improvement of multi-scale geomagnetic forcing specification will strongly enhance our understanding and capability to simulate the I-T system.