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- Title
Global Survey of Electron Precipitation due to Hiss Waves in the Earth's Plasmasphere and Plumes.
- Authors
Ma, Q.; Li, W.; Zhang, X. ‐J.; Bortnik, J.; Shen, X. ‐C.; Connor, H. K.; Boyd, A. J.; Kurth, W. S.; Hospodarsky, G. B.; Claudepierre, S. G.; Reeves, G. D.; Spence, H. E.
- Abstract
We present a global survey of energetic electron precipitation from the equatorial magnetosphere due to hiss waves in the plasmasphere and plumes. Using Van Allen Probes measurements, we calculate the pitch angle diffusion coefficients at the bounce loss cone, and evaluate the energy spectrum of precipitating electron flux. Our ∼6.5‐year survey shows that, during disturbed times, hiss inside the plasmasphere primarily causes the electron precipitation at L > 4 over 8 h < MLT < 18 h, and hiss waves in plumes cause the precipitation at L > 5 over 8 h < MLT < 14 h and L > 4 over 14 h < MLT < 20 h. The precipitating energy flux increases with increasing geomagnetic activity, and is typically higher in the plasmaspheric plume than the plasmasphere. The characteristic energy of precipitation increases from ∼20 keV at L = 6–∼100 keV at L = 3, potentially causing the loss of electrons at several hundred keV. Plain Language Summary: Hiss is a plasma wave with a broad frequency range spanning from tens to several thousand Hz, commonly observed in the dayside plasmasphere and plumes of the Earth's magnetosphere, and plays an important role in the loss of energetic electrons. Subject to the interaction with hiss waves, the radiation belt electrons precipitate from the equatorial magnetosphere into the Earth's upper atmosphere, potentially changing the ionospheric conductance and chemistry. Using the measurements of hiss waves and electrons from the ∼6.5‐year data of Van Allen Probes, we perform a global survey of electron precipitation due to hiss waves in the magnetosphere. Our survey indicates that hiss waves mostly cause the energetic electron precipitation in the dayside plasmasphere and in the afternoon sector of the plume. The precipitation is more significant during disturbed geomagnetic conditions than quiet times, and the precipitating flux is higher in the plasmaspheric plume than the plasmasphere. The characteristic energy of precipitating electrons increases with decreasing distance from the Earth. Although the average precipitating electron flux due to hiss is lower than that of chorus, the average energy of precipitation is higher, potentially causing the loss of relativistic electrons in the radiation belts. Key Points: During disturbed times, hiss waves cause enhanced electron precipitation in the dayside plasmasphere and plume in the afternoon sectorThe average total precipitating energy flux due to hiss waves reaches 0.3–1 erg/cm2/s at L > 4.5 and 8 h < MLT < 18 h when AE∗ > 500 nTAverage precipitating flux is higher in the plume than plasmasphere, and the precipitation energy increases with decreasing L shell
- Subjects
ELECTRON precipitation; MAGNETOSPHERE; PLASMASPHERE; VAN Allen radiation belts; ELECTRONS
- Publication
Journal of Geophysical Research. Space Physics, 2021, Vol 126, Issue 8, p1
- ISSN
2169-9380
- Publication type
Article
- DOI
10.1029/2021JA029644