Persistent Pitch Angle Anisotropies of Relativistic Electrons in the Outer Radiation Belts

A. D. Greeley; S. G. Kanekal; Quintin Schiller; Lauren Blum; Alexa J. Halford; Kyle Robert Murphy; Tero Raita; Daniel N. Baker

doi:10.1029/2023JA031549

Persistent Pitch Angle Anisotropies of Relativistic Electrons in the Outer Radiation Belts

A. D. Greeley^*, S. G. Kanekal, Quintin Schiller, Lauren Blum, Alexa J. Halford, Kyle Robert Murphy, Tero Raita, Daniel N. Baker

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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Abstract

Pitch angle distributions (PADs) in the radiation belts are well characterized with sinⁿ(α). By tracking the exponent “n,” termed pitch angle index, we are able to observe persistent and cross-energy changes in PADs of Van Allen radiation belt electrons using Van Allen Probes particle observations. The PAD measurements are well fit down to a single satellite spin, and therefore can track spatially and temporally confined changes to determine the connection between particles and waves. With this method, we study long-lasting and high-energy anisotropic electron PADs during a quiet period over 2 days, 26 and 27 June 2013. One potential driver for these changes is electromagnetic ion cyclotron wave interaction with the particles. We use several ground magnetometer stations from Canadian Array for Realtime Investigations of Magnetic Activity and Finnish pulsation magnetometer network of Sodankylä Geophysical Observatory to observe waves during the 2 days of interest. The connection between the waves and particles is inconclusive, although there is some temporal overlap of the phenomenon.

Original language	English
Article number	e2023JA031549
Number of pages	15
Journal	Journal of Geophysical Research: Space Physics
Volume	129
Issue number	1
Early online date	26 Dec 2023
DOIs	https://doi.org/10.1029/2023JA031549
Publication status	Published - 1 Jan 2024
Externally published	Yes

Keywords

EMIC waves
GOES
ground magnetometer
pitch angle distributions
radiation belts
Van Allen Probes

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10.1029/2023JA031549Licence: CC BY-NC-ND

JGR Space Physics - 2023 - Greeley - Persistent Pitch Angle Anisotropies of Relativistic Electrons in the Outer RadiationFinal published version, 5.82 MBLicence: CC BY-NC-ND

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abstract = "Pitch angle distributions (PADs) in the radiation belts are well characterized with sinn(α). By tracking the exponent “n,” termed pitch angle index, we are able to observe persistent and cross-energy changes in PADs of Van Allen radiation belt electrons using Van Allen Probes particle observations. The PAD measurements are well fit down to a single satellite spin, and therefore can track spatially and temporally confined changes to determine the connection between particles and waves. With this method, we study long-lasting and high-energy anisotropic electron PADs during a quiet period over 2 days, 26 and 27 June 2013. One potential driver for these changes is electromagnetic ion cyclotron wave interaction with the particles. We use several ground magnetometer stations from Canadian Array for Realtime Investigations of Magnetic Activity and Finnish pulsation magnetometer network of Sodankyl{\"a} Geophysical Observatory to observe waves during the 2 days of interest. The connection between the waves and particles is inconclusive, although there is some temporal overlap of the phenomenon.",

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note = "Funding information: The authors would like to thank the International Space Science Institute's (ISSI) International Teams program for support. A. D. Greeley, S. G. Kanekal, L. Blum, A. Halford, and K. Murphy are supported by and work with the Space Precipitation Impacts project at Goddard Space Flight Center through the Heliophysics Internal Science Funding Model.",

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AU - Halford, Alexa J.

AU - Murphy, Kyle Robert

AU - Raita, Tero

AU - Baker, Daniel N.

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N2 - Pitch angle distributions (PADs) in the radiation belts are well characterized with sinn(α). By tracking the exponent “n,” termed pitch angle index, we are able to observe persistent and cross-energy changes in PADs of Van Allen radiation belt electrons using Van Allen Probes particle observations. The PAD measurements are well fit down to a single satellite spin, and therefore can track spatially and temporally confined changes to determine the connection between particles and waves. With this method, we study long-lasting and high-energy anisotropic electron PADs during a quiet period over 2 days, 26 and 27 June 2013. One potential driver for these changes is electromagnetic ion cyclotron wave interaction with the particles. We use several ground magnetometer stations from Canadian Array for Realtime Investigations of Magnetic Activity and Finnish pulsation magnetometer network of Sodankylä Geophysical Observatory to observe waves during the 2 days of interest. The connection between the waves and particles is inconclusive, although there is some temporal overlap of the phenomenon.

AB - Pitch angle distributions (PADs) in the radiation belts are well characterized with sinn(α). By tracking the exponent “n,” termed pitch angle index, we are able to observe persistent and cross-energy changes in PADs of Van Allen radiation belt electrons using Van Allen Probes particle observations. The PAD measurements are well fit down to a single satellite spin, and therefore can track spatially and temporally confined changes to determine the connection between particles and waves. With this method, we study long-lasting and high-energy anisotropic electron PADs during a quiet period over 2 days, 26 and 27 June 2013. One potential driver for these changes is electromagnetic ion cyclotron wave interaction with the particles. We use several ground magnetometer stations from Canadian Array for Realtime Investigations of Magnetic Activity and Finnish pulsation magnetometer network of Sodankylä Geophysical Observatory to observe waves during the 2 days of interest. The connection between the waves and particles is inconclusive, although there is some temporal overlap of the phenomenon.

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Persistent Pitch Angle Anisotropies of Relativistic Electrons in the Outer Radiation Belts

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