Speaker
Description
Solar particle events (SPEs) are short-lived bursts of high-energy particles from the solar atmosphere and are important drivers of changes of the atmospheric chemistry. While most SPEs are relatively weak and have limited environmental impacts, evidence from cosmogenic radionuclides indicates that much stronger events have occurred in the past. The effects of such extreme SPEs depend strongly on the configuration of the Earth’s geomagnetic field, which modulates the penetration of energetic particles into the atmosphere. Periods of geomagnetic excursions, such as the Laschamps event (~41 ka), are characterized by a substantially weakened and reconfigured geomagnetic field, potentially enhancing the atmospheric impact of SPEs. Here, we investigate the effects of an extreme SPE under the reconstructed Laschamps geomagnetic field using the atmosphere–ocean–chemistry–climate model SOCOLv4. In contrast to previous idealized simulations assuming the absence of a geomagnetic field, the Laschamps reconstruction provides a spatially complex and physically consistent representation of geomagnetic shielding. We focus on the resulting changes in atmospheric composition, including NOx and HOx production, and their impact on ozone from the mesosphere to the surface. In addition, we examine the associated changes in atmospheric temperature, dynamics, and circulation.