GEM: Responses of Waves, Particles, and Precipitation to Solar Wind Dynamic Pressure Impulsive Changes

Solar wind dynamic pressure pulses are one of the most important sources that can largely affect the Earth’s magnetosphere-ionosphere system and include positive pressure pulse (PPP; step-like increase with time) and negative pressure pulse (NPP; step-like decrease with time). This research addresses a fundamental question regarding the effects of PPP and NPP on various magnetospheric waves, energetic electrons, and their precipitation, using multi-point satellite observations and modeling. The scientific results will significantly advance our current understanding of the Solar wind-Magnetosphere-Ionosphere coupling, specifically the wave-particle dynamics, and interactions in driving electron precipitation after solar wind dynamic pressure changes. This project will support three early career researchers and a graduate student. This project uses solar wind dynamic pressure and Sym-H index from the OMNI dataset to identify PPP and NPP events that hit the magnetosphere and are geoeffective. Satellites near the equator (i.e., THEMIS, Van Allen Probes, and MMS) provide plasma wave and electron measurements to evaluate their properties after pressure pulses. Low-Earth-Orbit (LEO) satellites (NOAA POES/MetOp) provide electron precipitation measurements to quantify the global distribution of pressure pulse-induced electron precipitation. Moreover, the Full Diffusion Code based on the quasi-linear theory will be used to calculate bounce-averaged diffusion coefficients, which will be further used to quantify electron precipitation driven by observed plasma waves (i.e., hiss, chorus, and electromagnetic ion cyclotron waves). By accomplishing these, the following science questions will be addressed. (1) How do magnetospheric plasma waves, including hiss, chorus, and electromagnetic ion cyclotron (EMIC) waves, respond to positive and negative solar wind pressure pulses at various L shells and magnetic local times (MLTs)? (2) How do the trapped energetic particles respond to positive and negative pressure pulses at various L-MLT regions? (3) How does the energetic particle precipitation respond to positive and negative pressure pulses at various L-MLT regions? (4) What are the relative roles of these magnetospheric waves in causing energetic particle precipitation during positive and negative pressure pulse events? 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.