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Bortnik et al. 2002
Bortnik, J., Inan, U.S. and Bell, T.F. (2002). L dependence of energetic electron precipitation driven by magnetospherically reflecting whistler waves. Journal of Geophysical Research 107: doi: 10.1029/2001JA000303. issn: 0148-0227.

Ray tracing analysis and a first-order treatment of the wave frequency and electron energy dependence of gyroresonant pitch angle scattering reveals the L shell dependence of the time-integrated energetic electron (>150 keV) precipitation flux in the drift loss cone due to a single cloud-to-ground lightning stroke. Primary features of the L dependence are determined by the ray paths of magnetospherically reflecting nonducted whistler waves, as well as the refraction of the wave normal vectors due to ionospheric horizontal electron density gradients at low latitudes. Calculations for lightning source latitudes of 25¿, 35¿, and 45¿, with an assumed average ionospheric electron density profile, as well as an International Reference Ionosphere model profile, indicate that horizontal ionospheric electron density gradients can cause the whistler wave energy to focus near the geomagnetic equator on the first magnetospheric traverse, resulting in a spatially narrow precipitation signature at low L shells (1.4 < L < 1.65). The magnitude of this low-L peak is found to be sensitively dependent on the local ionospheric density gradients. Subsequent magnetospheric reflections result in a broad precipitation peak at higher L shells (1.8 < L < 4.2), which is robustly present, with magnitude being relatively insensitive to lightning source-latitude and ionospheric horizontal gradients. The calculated L dependences were found to be in excellent agreement with drift-loss cone fluxes measured aboard the SAMPEX satellite.

BACKGROUND DATA FILES

Abstract

Keywords
Magnetospheric Physics, Energetic particles, precipitating, Space Plasma Physics, Wave/particle interactions, Magnetospheric Physics, Magnetosphere--inner, Magnetospheric Physics, Plasma waves and instabilities
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
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