Improved Performance by the TIE-GCM with the Inclusion of Helium as a Major Species

When considering the neutral constituents in the upper thermosphere and exosphere, helium needs to be accounted for as a major species. As detailed by Emmert (2015), most first-principle models do not consider helium a major species when solving for diffusion and collisions within the atmosphere. First-Principal, physics-based models hold a distinct spatial resolution advantage over empirical models which leads to a more realistic depiction of the atmosphere. NCAR's self-consistent, physics-based Thermosphere-Ionosphere-Electrodynamic General Circulation Model (TIE-GCM) has been updated to take into account this neutral constituent in its calculations. A prior study by Kim (2011) shows over a 100% RMS improvement in the neutral density values of the TIE-GCM when compared to the CHAMP satellite neutral densities when helium is included. This study incorporated weighted partial pressures of helium from the Naval Research Laboratory's MSIS Extension 2000 (NRLMSISE-00), an empirical model. This research initiated a TIE-GCM run with helium calculated directly as a major species and found improvement in neutral densities at altitudes above 600 km.