Investigating the Link Between Outer Radiation Belt Losses and Energetic Electron Escape at the Magnetopause: A Case Study Using Multi‐Mission Observations and Simulations

Abstract

Greater than tens of kiloelectronvolts energetic particles are regularly observed beyond the magnetopause at significantly higher intensities than expected from the solar wind and magnetosheath. However, the debate as to whether these particles (both electrons and ions) are of magnetospheric or solar origin began with the earliest in situ observations and has continued in the literature for several decades (e.g., review by Cohen et al., 2017, and references therein). The root of this debate focuses on whether these energetic particles originate from the solar wind and are accelerated near the bow shock (e.g., shock-drift or diffusive shock acceleration) or if they are magnetospheric particles that have escaped beyond the magnetopause (e.g., through either magnetic reconnection or escape due to finite gyroradius effects). The origin of these particles has wide implication for both heliophysics and planetary science, as similar observations

Statistical investigation on equatorial pitch angle distribution of energetic electrons in Earth’s outer radiation belt during CME- and CIR-driven storms

“…Interplanetary (IP) shocks generating strong electric field impulse can also cause rapid energization of radiation belt electrons within a time scale of few minutes (e.g., Foster et al (2015); Kanekal et al (2016)). The loss mechanism is driven by pitch-angle scattering of electrons and subsequent atmospheric precipitation led by wave-particle interactions (e.g., Thorne (1977); Rodger et al (2007); Reidy et al (2021)), or magnetopause shadowing caused by sudden magnetospheric compression (e.g., Yu et al (2013); Staples et al (2020); Cohen et al (2021)), or a combination of both (e.g., Summers and Thorne (2003); Bortnik et al (2006); Shprits et al (2006); Ukhorskiy et al (2006); Turner et al (2012); Blum et al (2015); Shprits et al (2017)). The relativistic electron dynamics also show strong dependence on several factors, such as, geomagnetic activity, solar wind driving conditions, spatial location, local time, and background magnetospheric conditions (e.g., Li et al (1997); Reeves et al (1998Reeves et al ( , 2003; Meredith et al (2003); Lee et al (2013); Ni et al (2013); Thorne et al (2013b,a); Baker et al (2013Baker et al ( , 2014b).…”

Phase Space Density Analysis of Outer Radiation Belt Electron Energization and Loss During Geoeffective and Nongeoeffective Sheath Regions

“…Future work will target events after August 2015 when data from the Magnetospheric Multiscale Mission (MMS) is available. The orbit of MMS allows investigation of PSD distributions beyond Van Allen Probes apogee eliminating the ambiguity of PSD gradients near geosynchronous orbit (e.g., Cohen et al., 2021).…”

Comprehensive Observations of Magnetospheric Particle Acceleration, Sources, and Sinks (COMPASS): A Mission Concept to Jupiter’s Extreme Magnetosphere to Address Fundamental Mysteries in Heliophysics

“…Acceleration from radial transport may prove to be a dominant process, which arises from inward radial diffusion (e.g., Kollmann et al, 2018) driven by: random field fluctuations in the magnetosphere or the ionosphere (e.g., Lejosne & Kollmann, 2020), centrifugally driven interchange (e.g., Mauk et al, 2002), or large-scale coherent transport (e.g., Hao et al, 2020). Non-adiabatic transport may occur during reconnection in the Jovian magnetodisk and/or magnetotail (e.g., Vogt et al, 2020) or at low altitudes (Masters et al, 2021), leading to acceleration processes that are in principle similar to those found in Earth's magnetotail (e.g., Turner et al, 2021;Cohen et al, 2021). One of the major thrusts of COMPASS is to cleanlymeaning high signal to noise through whatever means necessary-measure energy-and pitch-angle-resolved differential 1 MeV to > 50 MeV electron fluxes, 1 MeV to 1 GeV proton fluxes, and 1 MeV/nuc to > 1 GeV/nuc heavier ion fluxes in conjunction with a full spectrum of plasma wave measurements.…”

“…Acceleration through adiabatic transport may arise from inward radial diffusion (De Pater and Goertz, 1994;Kollmann et al, 2018;Nenon et al, 2018) driven by random field fluctuations in the magnetosphere or the ionosphere (Lejosne and Kollmann, 2020), centrifugally driven interchange (Mauk et al, 2002), or convective transport via large-scale coherent plasma flows (Hao, Sun, Roussos, et al, 2020). Non-adiabatic transport may occur during COMPASS: A Heliophysics Mission Concept Study to Explore the Extremes of Jupiter's Magnetosphere A-3 reconnection (Vasyliunas et al, 1983;Vogt et al, 2010, Ebert et al, 2017, leading to acceleration processes similar to those found in Earth's magnetotail (e.g., Cohen et al, 2021;Turner et al 2021).…”