Atmospheric Ionization Module Osnabrück (AIMOS): A 3‐D model to determine atmospheric ionization by energetic charged particles from different populations

Abstract

[1] We present a 3-D numerical model of atmospheric ionization due to precipitating particles with high spatial resolution. The Atmospheric Ionization Model Osnabrück (AIMOS) consists of two parts: a GEANT4-based Monte Carlo simulation and a sorting algorithm to assign observations from two polar-orbiting satellites to horizontal precipitation cells, depending on geomagnetic activity. The main results are as follows:(1) the sorting algorithm and thus the 3-D mapping of particle fluxes works reasonably well; (2) ionization rates are in good agreement with the ones from earlier models; (3) during quiet times, the major contribution to ionospheric ionization is from electrons both in the polar cap (solar electrons) as well as in the auroral oval (magnetospheric electrons) with the ionization in the auroral oval exceeding that in the polar cap; (4) during solar particle events the dominant effect in the polar cap in the stratosphere and mesosphere is from solar protons although solar electrons can contribute up to 30% to the ionization; (5) during strong shocks following a solar particle event, in the auroral oval magnetospheric electrons and protons lead to ionization rates of up to some 10% of the ones of solar particles; and (6) independent of particle source and precipitation site, in general, ionization by electrons is more important in the thermosphere.

NO<sub><i>y</i></sub> production, ozone loss and changes in net radiative heating due to energetic particle precipitation in 2002–2010

“…Temporal LIMA data are made available to 3dCTM every 6 h; 3dCTM uses a family approach for neutral gas-phase constituents in the stratosphere at altitudes below the 0.33 hPa level, but not in the mesosphere and lower thermosphere. The impact of energetic particles is considered by prescribed ionization rates for precipitation of electrons, proton and alphas from the AIMOS model (Wissing and Kallenrode, 2009), version v1.6. Photoionization of N 2 , O 2 , N and O in the EUV and NO photoionization in the Ly-α band has been included as well.…”

“…In the mesosphere, the family members are transported separately. To consider the impact of energetic particle precipitation, proton and electron ionization rates from the AIMOS model (Wissing and Kallenrode, 2009) version v1.6 are prescribed; 1.25 NO x per ion pair are produced with a partitioning between N and NO of 45 and 55 % as described in Porter et al (1976) and Jackman et al (2005); 0-2 HO x per ion pair are formed following Solomon et al (1981).…”

Composition changes after the "Halloween" solar proton event: the High Energy Particle Precipitation in the Atmosphere (HEPPA) model versus MIPAS data intercomparison study

“…As particle precipitation strongly depends on the geomagnetic field, the model accounts for different spatial precipitation zones. A detailed description of AIMOS can be found in Wissing and Kallenrode (2009). AIMOS is composed of two parts.…”

“…In order to reduce the model variability and to make differences between the simulations more traceable, we have simplified the intercomparison setup such that a common particle-induced ionization source has been used in all models. These ionization rates, accounting for protons (154 eV-500 MeV) and electrons (154 eV-5 MeV) have been provided by the AIMOS model (Wissing and Kallenrode, 2009). Different model responses to the particle forcing are hence reduced to differences of the intrinsic model properties, e.g.…”

Energetic particle induced intra-seasonal variability of ozone inside the Antarctic polar vortex observed in satellite data

“…After a multi-year two-dimensional model spin-up, two simulations from 2003 to 2009 were performed. The first run (base run) does not consider any energetic particles, while the second run (EP run) includes ionisation effects by both protons and electrons, using the ionisation rates provided by the Atmospheric Ionisation Module Osnabrück (AIMOS; Wissing and Kallenrode, 2009). The resulting NO x production per created ion pair includes various ionic and neutral reactions depending on the atmospheric background state (Nieder et al, 2014).…”