Radiation belt electron precipitation due to VLF transmitters: Satellite observations

• Published in: Geophysical research letters Vol. 35; no. 9; pp. L09101 - n/a
• Main Authors: Sauvaud, J.-A., Maggiolo, R., Jacquey, C., Parrot, M., Berthelier, J.-J., Gamble, R. J., Rodger, Craig J.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 01.05.2008; Blackwell Publishing Ltd
• Subjects: Astrophysics; Cosmology and Extra-Galactic Astrophysics; Earth sciences; Earth, ocean, space; Energetic particles; Exact sciences and technology; inner belt; Magnetospheric Physics; Physics; precipitating; Radiation belts; Sciences of the Universe; Space Plasma Physics; Space radiation environment; Space Weather; trapped; VLF transmitters; wave-particle interaction; Wave/particle interactions; Narrows; New York; United States; wave-particle interaction; inner belt; VLF transmitters; altitude; keV range; Storm activity; magnetic storms; Ionospheric absorption; Electron precipitation; Pitch angle; Relativistic electron; global; clouds; Inner radiation belt; North America; Whistler wave; frequency; Source strength; Earth; particles; Electron flux; satellites; Space remote sensing; Radiation belt; Satellite observation; Loss cone; magnetosphere; correlation
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2008GL033194

In the Earth's inner magnetosphere, the distribution of energetic electrons is controlled by pitch‐angle scattering by waves. A category of Whistler waves originates from powerful ground‐based VLF transmitter signals in the frequency range 10–25 kHz. These transmissions are observed in space as waves of very narrow bandwidth. Here we examine the significance of the VLF transmitter NWC on the inner radiation belt using DEMETER satellite global observations at low altitudes. We find that enhancements in the ∼100–600 keV drift‐loss cone electron fluxes at L values between 1.4 and 1.7 are linked to NWC operation and to ionospheric absorption. Waves and particles interact in the vicinity of the magnetic equatorial plane. Using Demeter passes across the drifting cloud of electrons caused by the transmitter; we find that ∼300 times more 200 keV electrons are driven into the drift‐loss cone during NWC transmission periods than during non‐transmission periods. The correlation between the flux of resonant electrons and the Dst index shows that the electron source intensity is controlled by magnetic storm activity.