Energetic Electron Precipitation: Multievent Analysis of Its Spatial Extent During EMIC Wave Activity

Journal Article · Sat Mar 09 00:00:00 EST 2019 · Journal of Geophysical Research. Space Physics

DOI:https://doi.org/10.1029/2018JA026291· OSTI ID:1597373

Capannolo, L. ^[1]; Li, W. ^[1]; Ma, Q. ^[2]; Shen, X. ‐C. ^[1]; Zhang, X. ‐J. ^[3]; Redmon, R. J. ^[4]; Rodriguez, J. V. ^[5]; Engebretson, M. J. ^[6]; Kletzing, C. A. ^[7]; Kurth, W. S. ^[7]; Hospodarsky, G. B. ^[7]; Spence, H. E. ^[8]; Reeves, G. D. ^[9]; Raita, T. ^[10]

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1. Boston Univ., MA (United States). Center for Space Physics
2. Boston Univ., MA (United States). Center for Space Physics; Univ. of California, Los Angeles, CA (United States)
3. Univ. of California, Los Angeles, CA (United States)
4. Univ. of Colorado, Boulder, CO (United States). Cooperative Inst. for Research in Environmental Sciences
5. Univ. of Colorado, Boulder, CO (United States). Cooperative Inst. for Research in Environmental Sciences; National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States)
6. Univ. of Minnesota, Minneapolis, MN (United States)
7. Univ. of Iowa, Iowa City, IA (United States)
8. Univ. of New Hampshire, Durham, NH (United States). Inst. for the Study of Earth, Oceans, and Space
9. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Space Science and Applications Group
10. Univ. of Oulu, Sodankylä (Finland). Sodankylä Geophysical Observatory

Electromagnetic ion cyclotron (EMIC) waves can drive precipitation of tens of keV protons and relativistic electrons, and are a potential candidate for causing radiation belt flux dropouts. In this study, we quantitatively analyze three cases of EMIC-driven precipitation, which occurred near the dusk sector observed by multiple Low-Earth-Orbiting (LEO) Polar Operational Environmental Satellites/Meteorological Operational satellite programme (POES/MetOp) satellites. During EMIC wave activity, the proton precipitation occurred from few tens of keV up to hundreds of keV, while the electron precipitation was mainly at relativistic energies. We compare observations of electron precipitation with calculations using quasi-linear theory. For all cases, we consider the effects of other magnetospheric waves observed simultaneously with EMIC waves, namely, plasmaspheric hiss and magnetosonic waves, and find that the electron precipitation at MeV energies was predominantly caused by EMIC-driven pitch angle scattering. Interestingly, each precipitation event observed by a LEO satellite extended over a limited L shell region (ΔL ~ 0.3 on average), suggesting that the pitch angle scattering caused by EMIC waves occurs only when favorable conditions are met, likely in a localized region. Furthermore, we take advantage of the LEO constellation to explore the occurrence of precipitation at different L shells and magnetic local time sectors, simultaneously with EMIC wave observations near the equator (detected by Van Allen Probes) or at the ground (measured by magnetometers). Our analysis shows that although EMIC waves drove precipitation only in a narrow ΔL, electron precipitation was triggered at various locations as identified by POES/MetOp over a rather broad region (up to ~4.4 hr MLT and ~1.4 L shells) with similar patterns between satellites.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: National Aeronautic and Space Administration (NASA)
• Grant/Contract Number: 89233218CNA000001
• OSTI ID: 1597373
• Report Number(s): LA-UR--19-32273
• Journal Information: Journal of Geophysical Research. Space Physics, Journal Name: Journal of Geophysical Research. Space Physics Journal Issue: 4 Vol. 124; ISSN 2169-9380
• Publisher: American Geophysical Union
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
EMIC waves
Heliospheric physics
Magnetospheric Physics
energetic electron precipitation
pitch angle scattering
quasi‐linear theory
radiation belts dropouts