Particle Precipitation: Drivers, Properties, and Impacts on Atmosphere, Ionosphere, Magnetosphere (AIM) Coupling

Energetic particle precipitation (EPP) is one of the fundamental drivers of space weather in the coupled atmosphere-ionosphere-magnetosphere (AIM) system. These electrons and ions from the sun or the terrestrial magnetosphere, ranging in energy from hundreds of eV to GeV, precipitate into the atmosphere in response to enhanced topside (solar and magnetosphere) driving. They deposit their energy at a wide range of altitudes, enhancing ionization, and changing neutral temperature, density, and winds. During times of prolonged geomagnetic activity or solar energetic particle events the resulting changes can adversely affect anthropogenic systems including disruption of communication and power systems, and increased satellite drag leading to orbital decay.
In addition to its effects on space weather, EPP has been recognized as an important component of climate (World Meteorological Organization (WMO), 2018) via its ability to indirectly destroy ozone, modifying local radiative balance in the middle and upper atmosphere. Despite the recognized importance of EPP to the AIM system, the way in which these systems interact is highly complex and remains poorly understood and constrained. In particular, the AIM is a strongly two-way coupled system whereby EPP input drives ion outflow that in turn modulates EPP. This coupling varies by location and over a wide range of spatial and temporal scales.
Measurements from our current observational fleet are not able to fully capture EPP-driven AIM dynamics. As a result, we lack a fundamental understanding of many aspects of this coupled system, and models cannot be validated and are inhibited in their ability to forecast space weather. To compound this situation, different aspects of the AIM system are studied by the different communities with insufficient cross-community cooperation. Properly studying AIM dynamics, a societal level priority, requires a global systems science (holistic) approach to data collection, analysis, and modeling.
These topics, addressed in this talk, are the focus of a Chapman conference, to be held in February 2025 in Melbourne, Australia, and we invite the participation of interested scientists and students.