In the project "Understanding the influence of the SPace Environment on Atmospheric CHemistry and dynamics", we investigate the impact of energetic particles on the middle atmosphere and the climate system. Special focus is on electrons from the radiation belts precipitating into the atmosphere during geomagnetic storms. Precipitating electron fluxes are measured by particle detectors on low-Earth polar-orbiting satellites. However it has been shown that forcing data based on these observations tend to underestimate atmospheric ionization and its impact on the chemical composition of the atmosphere.

Within the SPEACH project, we are using a new approach to tackle this problem. We combine modelling of electrons in the magnetosphere driven by solar wind with modelling of the middle atmosphere. We use the VERB-4D magnetosphere model, led by GFZ, to simulate processes in the magnetosphere during different types of geomagnetic storms and calculate electron fluxes lost into the Earth’s atmosphere. These precipitating electrons will then serve as an input for chemistry-climate simulations of the middle atmosphere down to the surface with the dedicated model EMAC.