Solar Energetic Proton Access to the Inner Magnetosphere During the September 7–8, 2017 Event. Issue 7 (12th July 2021)

• Record Type: Journal Article
• Authors: Li, Zhao; Engel, Miles; Hudson, Mary; Kress, Brian; Patel, Maulik; Qin, Murong; Selesnick, Richard
• Is Part Of: Journal of geophysical research. Volume 126:Issue 7(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-07-12
• Subjects: Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2021JA029107
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: The access of solar energetic protons into the inner magnetosphere on September 7–8, 2017 is investigated by following reversed proton trajectories to compute the proton cutoff energy using the Dartmouth geomagnetic cutoff code (Kress et al., 2010, https://doi.org/10.1029/2009sw000488 ). The cutoff energies for protons coming from the west and east direction, the minimum and maximum cutoff energy respectively, are calculated every 5 min along the orbit of Van Allen Probes using TS07 and the Lyon‐Fedder‐Mobarry (LFM) MHD magnetic field model. The result shows that the cutoff energy increases significantly as the radial distance decreases, and that the cutoff energy decreases with the building up of the ring current during magnetic storms. Solar wind dynamic pressure also affects cutoff suppression (Kress et al., 2004, https://doi.org/10.1029/2003gl018599 ). The LFM‐RCM model shows stronger suppression of cutoff energy than TS07 during strong solar wind driving conditions. The simulation result is compared with proton flux measurements, showing consistent variation of the cutoff location during the September 7–8, 2017 geomagnetic storm. Key Points: The Dartmouth geomagnetic cutoff code is updated with TS07 and LFM MHD magnetic field snapshots The proton cutoff energy is calculated during the September 7–8, 2017 SEP event Comparison with data shows better correlation using LFM than TS04 and TS07