Department of Atmospheric and Oceanic Sciences University of California, Los Angeles Los Angeles CA USA
Department of Atmospheric and Oceanic Sciences University of California, Los Angeles Los Angeles CA USA, Center for Space Physics Boston University Boston MA USA
Department of Mathematics, Physics and Electrical Engineering Northumbria University Newcastle upon Tyne UK
Mullard Space Science Laboratory University College London London UK
We analyzed the contribution of electromagnetic ion cyclotron (EMIC) wave driven electron loss to a flux dropout event in September 2017. The evolution of electron phase space density (PSD) through the dropout showed the formation of a radially peaked PSD profile as electrons were lost at high L* , resembling distributions created by magnetopause shadowing. By comparing 2D Fokker Planck simulations of pitch angle diffusion to the observed change in PSD, we found that the μ and K of electron loss aligned with maximum scattering rates at dropout onset. We conclude that, during this dropout event, EMIC waves produced substantial electron loss. Because pitch angle diffusion occurred on closed drift paths near the last closed drift shell, no radial PSD minimum was observed. Therefore, the radial PSD gradients resembled solely magnetopause shadowing loss, even though the local pitch angle scattering produced electron losses of several orders of magnitude of the PSD.
Staples, F. A., et al. "Differentiating Between Simultaneous Loss Drivers in Earth's Outer Radiation Belt: Multi‐Dimensional Phase Space Density Analysis." Geophysical Research Letters, vol. 50, no. 23, Dec. 2023. https://doi.org/10.1029/2023GL106162
Staples, F. A., Ma, Q., Kellerman, A., Rae, I. J., Forsyth, C., Sandhu, J. K., & Bortnik, J. (2023). Differentiating Between Simultaneous Loss Drivers in Earth's Outer Radiation Belt: Multi‐Dimensional Phase Space Density Analysis. Geophysical Research Letters, 50(23). https://doi.org/10.1029/2023GL106162
Staples, F. A., Ma, Q., Kellerman, A., et al., "Differentiating Between Simultaneous Loss Drivers in Earth's Outer Radiation Belt: Multi‐Dimensional Phase Space Density Analysis," Geophysical Research Letters 50, no. 23 (2023), https://doi.org/10.1029/2023GL106162
@article{osti_2229204,
author = {Staples, F. A. and Ma, Q. and Kellerman, A. and Rae, I. J. and Forsyth, C. and Sandhu, J. K. and Bortnik, J.},
title = {Differentiating Between Simultaneous Loss Drivers in Earth's Outer Radiation Belt: Multi‐Dimensional Phase Space Density Analysis},
annote = {Abstract We analyzed the contribution of electromagnetic ion cyclotron (EMIC) wave driven electron loss to a flux dropout event in September 2017. The evolution of electron phase space density (PSD) through the dropout showed the formation of a radially peaked PSD profile as electrons were lost at high L* , resembling distributions created by magnetopause shadowing. By comparing 2D Fokker Planck simulations of pitch angle diffusion to the observed change in PSD, we found that the μ and K of electron loss aligned with maximum scattering rates at dropout onset. We conclude that, during this dropout event, EMIC waves produced substantial electron loss. Because pitch angle diffusion occurred on closed drift paths near the last closed drift shell, no radial PSD minimum was observed. Therefore, the radial PSD gradients resembled solely magnetopause shadowing loss, even though the local pitch angle scattering produced electron losses of several orders of magnitude of the PSD. },
doi = {10.1029/2023GL106162},
url = {https://www.osti.gov/biblio/2229204},
journal = {Geophysical Research Letters},
issn = {ISSN 0094-8276},
number = {23},
volume = {50},
place = {United States},
publisher = {American Geophysical Union (AGU)},
year = {2023},
month = {12}}