Contribution of ULF wave activity to the global recovery of the outer radiation belt during the passage of a high-speed solar wind stream observed in September 2014

TitleContribution of ULF wave activity to the global recovery of the outer radiation belt during the passage of a high-speed solar wind stream observed in September 2014
Publication TypeJournal Article
Year of Publication2019
AuthorsDa Silva, LA, Sibeck, D, Alves, LR, Souza, VM, Jauer, PR, Claudepierre, SG, Marchezi, JP, Agapitov, O, Medeiros, C, Vieira, LEA, Wang, C, Jiankui, S, Liu, Z, Gonzalez, W, Dal Lago, A, Rockenbach, M, Padua, MB, Alves, MV, Barbosa, MVG, Fok, M-C, Baker, D, Kletzing, C, Kanekal, SG, Georgiou, M
JournalJournal of Geophysical Research: Space Physics
Date Published02/2019
Keywordsalfvén fluctuations; Earth's magnetosphere; high speed stream; Radiation belts; relativistic electron flux; ULF wave; Van Allen Probes
AbstractEnergy coupling between the solar wind and the Earth's magnetosphere can affect the electron population in the outer radiation belt. However, the precise role of different internal and external mechanisms that leads to changes of the relativistic electron population is not entirely known. This paper describes how Ultra Low Frequency (ULF) wave activity during the passage of Alfvénic solar wind streams contributes to the global recovery of the relativistic electron population in the outer radiation belt. To investigate the contribution of the ULF waves, we searched the Van Allen Probes data for a period in which we can clearly distinguish the enhancement of electron fluxes from the background. We found that the global recovery that started on September 22, 2014, which coincides with the corotating interaction region preceding a high‐speed stream and the occurrence of persistent substorm activity, provides an excellent scenario to explore the contribution of ULF waves. To support our analyses, we employed ground and space‐based observational data, global magnetohydrodynamic (MHD) simulations, and calculated the ULF wave radial diffusion coefficients employing an empirical model. Observations show a gradual increase of electron fluxes in the outer radiation belt and a concomitant enhancement of ULF activity that spreads from higher to lower L‐shells. MHD simulation results agree with observed ULF wave activity in the magnetotail, which leads to both fast and Alfvén modes in the magnetospheric nightside sector. The observations agree with the empirical model and are confirmed by Phase Space Density (PhSD) calculations for this global recovery period.
URLhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026184
DOI10.1029/2018JA026184
Short TitleJ. Geophys. Res. Space Physics


Page Last Modified: March 1, 2019