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Global Survey of Plasma Sheet Electron Precipitation due to Whistler Mode Chorus Waves in Earth's Magnetosphere
Journal article   Open access   Peer reviewed

Global Survey of Plasma Sheet Electron Precipitation due to Whistler Mode Chorus Waves in Earth's Magnetosphere

Q. Ma, H. K. Connor, X.‐J. Zhang, W. Li, X.‐C. Shen, D. Gillespie, C. A. Kletzing, W. S. Kurth, G. B. Hospodarsky, S. G. Claudepierre, …
Geophysical research letters, Vol.47(15), e2020GL088798
08/16/2020
DOI: 10.1029/2020GL088798
url
https://doi.org/10.1029/2020GL088798View
Published (Version of record) Open Access

Abstract

Whistler mode chorus waves can scatter plasma sheet electrons into the loss cone and produce the Earth's diffuse aurora. Van Allen Probes observed plasma sheet electron injections and intense chorus waves on 24 November 2012. We use quasilinear theory to calculate the precipitating electron fluxes, demonstrating that the chorus waves could lead to high differential energy fluxes of precipitating electrons with characteristic energies of 10–30 keV. Using this method, we calculate the precipitating electron flux from 2012 to 2019 when the Van Allen Probes were near the magnetic equator and perform global surveys of electron precipitation under different geomagnetic conditions. The most significant electron precipitation due to chorus is found from the nightside to dawn sectors over 4 < L < 6.5. The average total precipitating energy flux is enhanced during disturbed conditions, with time‐averaged values reaching ~3–10 erg/cm2/s when AE ≥ 500 nT. Plain Language Summary Whistler mode chorus is an electromagnetic emission present in the low‐density region of Earth's magnetosphere. Chorus waves can change the electron distribution in the plasma sheet to cause electron precipitation into Earth's upper atmosphere, leading to the diffuse aurora. We use satellite measurements of waves and electrons to quantify the electron precipitation from the plasma sheet to the upper atmosphere. An event study is presented to demonstrate that intense chorus waves observed near the magnetic equator can cause high energy fluxes of precipitating electrons with characteristic energy of 10–30 keV. To obtain the statistics of the electron precipitation, we calculate the precipitating electron flux from 2012 to 2019 using wave and electron measurements near the magnetic equator. Our survey indicates that chorus waves can cause the precipitation from the nightside to dawn sectors, over an equatorial radial distance of 4–6.5 Earth radii. The energy flux of electron precipitation is enhanced during disturbed geomagnetic conditions compared to quiet conditions. Our study provides the quantification of the empirical electron precipitation from the plasma sheet due to chorus on a global scale. Key Points We evaluate the electron precipitation due to whistler mode chorus waves and perform a global survey of the precipitating flux at L < 6.5 The chorus waves cause the precipitation of 1‐ to 100‐keV electrons predominantly from the nightside to dawn sectors over 4 < L < 6.5 Average total precipitating energy flux is enhanced during disturbed conditions, reaching 3–10 erg/cm2/s when AE > 500 nT
 chorus wave electron precipitation plasma sheet electron Van Allen Probes observation

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