SHINE: Understanding the Impact of Solar Energetic Particles and Forbush Decreases on the Global Electric Circuit

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Solar Energetic Particle (SEP) are identified as the top space weather hazard. These particles, when propagating to the Earth, create risks to astronauts, electronics onboard satellites, and to other human-built infrastructure and technology. Previous studies have suggested that SEPs can even influence Earth’s climate. As these particles precipitate down in the Earth’s atmosphere, they deposit their energy through ionization, modify atmospheric chemistry, and lead to cloud formation. The coupling between SEP-related space weather phenomena and tropospheric climate can be essential for the human environment, and this coupling exists, in part, through the Global Electric Circuit (GEC). A thorough understanding of this coupling requires a thorough understanding of how the GEC responds to SEPs and Forbush Decreases (FDs), and requires collaborative efforts from researchers from heliospheric physics, cosmic ray physics, and atmospheric physics. This project is an interdisciplinary study to increase understanding on how SEPs affect the GEC and terrestrial weather or climate. This proposal will support one postdoc and a summer graduate student, therefore helping to train the next generation of space plasma and atmospheric scientists. This work aims to understand the effect of SEPs and FDs on the Global Electric Circuit. It will focus on how the measured potential gradient (PG) in fair weather conditions responds to SEPs and FDs across the globe and how lightning respond to SEPs and FDs. The methodology will involve both data analysis and numerical simulation. To achieve the science goals the team will, 1) Examine the correlation between PG increases in fair weather conditions and station altitude and magnetic latitude; 2) Identify the possible relationship between the characteristics of SEPs and solar wind and the PG increases in fair weather condition; 3) Identify the possible relationship between Forbush Decrease characteristics and PG increases in fair weather conditions; 4) Understand the global ionization profiles during SEP events by comparing observations of PG increases with Monte-Carlo simulations; and 5) Investigate the relationship between SEP events and lightning.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.