Self-consistent global transport of metallic ions with WACCM-X

Abstract

The NCAR Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension (WACCM-X) v2.1 has been extended to include the neutral and ion-molecule chemistry and dynamics of three metals (Mg, Na, and Fe), which are injected into the upper mesosphere-lower thermosphere by meteoric ablation. Here we focus on the self-consistent electrodynamical transport of metallic ions in both the E and F regions. The model with full ion transport significantly improves the simulation of global distribution and seasonal variations of Mg+, although the peak density is slightly lower (about 35ĝ€¯% lower in peak density) compared with the SCIAMACHY measurements. Near the magnetic equator, the diurnal variation in upward and downward transport of Mg+ is generally consistent with the "ionosphere fountain effect". The thermospheric distribution of Fe is shown to be closely coupled to the transport of Fe+. The effect of ion mass on ion transport is also examined: The lighter ions (Mg+ and Na+) are transported above 150ĝ€¯km more easily than the heavy Fe+. We also examine the impact of the transport of major molecular ions, NO+ and O2+, on the distribution of metallic ions.