Understanding the influence of the SPace Environment on Atmospheric CHemistry and dynamics (SPEACH)

• Applicants: Professor Dr. Yuri Shprits, Ph.D.; Dr. Miriam Sinnhuber
• Subject Area: Atmospheric Science
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 434829450

Energetic electrons from the aurora and the radiation belts are known sources of nitric oxide in the auroral region of the upper mesosphere and lower thermosphere (60-140 km). During polar winter, auroral nitric oxide is transported down to the mid-stratosphere (30-45 km), with values varying with geomagnetic activity and the dynamical state of the atmosphere. Here, nitric oxides destroy ozone very efficiently; as ozone is one of the key species of radiative heating and cooling in the stratosphere, downward transport of auroral NOx into the stratosphere leads to changes in temperatures and wind fields that can propagate throughout the atmosphere and even affect tropospheric weather systems. Geomagnetic activity is therefore now recommended as part of the solar forcing of the climate system for the upcoming CMIP-6 (IPCC) model experiments for the first time. However, the atmospheric ionization rates needed to drive these model experiments are based empirically on fluxes of precipitating electrons which carry a large uncertainty, and recent studies suggest that there may be serious problems with the accuracy of these data.In this project, we will investigate the underlying processes in detail to improve their representation in global models, both in the magnetosphere driven by the solar wind, and in the middle atmosphere as represented in changes in atmospheric composition, temperature and wind fields.In particular, we will address the following science questions:• How do conditions in the magnetosphere and driven by the solar wind affect the precipitation of ring current electrons into the atmosphere?• What is the energy spectrum of the precipitating electrons accelerated in the magnetosphere in different types of geomagnetic storms?• Which energy range of the precipitating electrons has the largest impact on the chemistry and dynamics of the middle atmosphere?To address these questions, we will perform simulations with the newly developed VERB-4D code to model electron precipitation driven by wave-particle interactions with chorus, plasmaspheric hiss, hiss in plumes, and EMIC waves. Results of the simulations will be validated against NOAA POES data. Modeled electron fluxes will be used as input in the chemistry-climate model EMAC/EDITh (surface to 220 km) at the top of the model domain. Modeled temperature and nitric oxide will be validated against observations. Case studies will be carried out for a set of Co-rotating Interaction Regions (CIR) and solar Coronal mass ejections (CMEs) driven storms and during quiet geomagnetic conditions, to investigate how the different loss processes affect different atmospheric regions.

• DFG Programme: Research Grants