The Atmospheric Ionization during Substorm Model (AISstorm 2.1)

Abstract

AISstorm derives the global atmospheric ionization due to particle precipitation based on in-situ particle measurements. The model covers auroral precipitation as well as solar particle events on an altitude range of about 250km down to 16km for protons and down to 70km for electrons. Alpha particle ionization is included as well but on a smaller altitude range. The overall structure splits up into an empirical model that determines the 2D precipitating particle flux and a numerical model that determines the ionization profile of single particles. The combination of these two results in a high resolution 3D particle ionization rate pattern. The AISstorm is the successor of the Atmospheric Ionization Module Osnabrück (AIMOS). The main benefit of the updated ionization rates are higher dynamics during substorms and during the onset of geomagnetic storms in particular in the mesosphere - in agreement with observations. The internal structure of the model has been completely revised in AISstorm with the main aspects being: a) an internal magnetic coordinate system, b) including substorms characteristics, c) higher time resolution, d) higher spatial resolution, e) energy specific separate handling of auroral precipitation, polar cap precipitation and crosstalk affected areas, f) better MLT resolution. The contribution will compare the new ionization rates to AIMOS 1.6, AISstorm 2.0 and the HEPPA III multi-model study.