edu.ucar.opensky::articles:24453 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-25T06:29:22.946384 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7251nms Dependence of relativistic electron precipitation in the ionosphere on EMIC wave minimum resonant energy at the conjugate equator 2021-05-01T00:00:00Z publication https://n2t.org/ark:/85065/d7251nms https://doi.org/10.1029/2021JA029193 ZHANG, X. author Mourenas, D. author Shen, X. author Qin, Murong author Artemyev, A. V. author Ma, Q. author Li, W. author Hudson, M. K. author Angelopoulos, V. author UCAR/NCAR - Library publisher We investigate relativistic electron precipitation events detected by Polar Environmental Satellites (POES) in low-Earth orbit in close conjunction with Van Allen Probe A observations of electromagnetic ion cyclotron (EMIC) waves near the geomagnetic equator. We show that the occurrence rate of >0.7 MeV electron precipitation recorded by POES during those times strongly increases, reaching statistically significant levels when the minimum electron energy for cyclotron resonance with hydrogen or helium band EMIC waves at the equator decreases below similar or equal to 1.0-2.5 MeV, as expected from the quasi-linear theory. Both hydrogen and helium band EMIC waves can be effective in precipitating MeV electrons. However, >0.7 MeV electron precipitation is more often observed (at statistically significant levels) when the minimum electron energy for cyclotron resonance with hydrogen band waves is low (E-min = 0.6-1.0 MeV), whereas it is more often observed when the minimum electron energy for cyclotron resonance with helium band waves is slightly larger (E-min = 1.0-2.5 MeV). This is indicative of the warm plasma effects for waves approaching the He+ gyrofrequency. We further show that most precipitation events had energies > 0.7-1.0 MeV, consistent with the estimated minimum energy (E-min similar to 0.6 - 2.5 MeV) of cyclotron resonance with the observed EMIC waves during the majority of these events. However, 4 out of the 12 detected precipitation events cannot be explained by electron quasi-linear scattering by the observed EMIC waves, and 12 out of 20 theoretically expected precipitation events were not detected by POES, suggesting the possibility of nonlinear effects likely present near the magnetic equator, or warm plasma effects, and/or narrowly localized bursts of EMIC waves. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright 2021 American Geophysical Union. None eng geoscientificInformation