Precipitation of radiation belt electrons by obliquely-propagating lightning-generated whistler waves

This dissertation presents a formulation for calculating the transient precipitation of energetic radiation belt electrons which results from gyroresonance scattering induced by obliquely-propagating whistler-mode waves throughout broad regions of the magnetosphere, with application to VLF whistlers generated by individual atmospheric lightning discharges. The formulation is applied for representative lightning locations as a means to assess the loss of energetic electrons from the Earth's magnetosphere and associated energy deposition to the upper atmosphere which occurs in response to global lightning activity.;The method utilizes a comprehensive raytracing technique to first determine the spatially varying oblique whistler wave properties (wave normal angle, power density and propagation delay) throughout the magnetosphere over the broadband frequency range f = 200 Hz; to 10 kHz, for a set of assumed lightning source geomagnetic latitudes ls = 20°, 30°, 40° and 50°, and subsequently employs a test particle formulation to calculate the energy-time signatures of the precipitating energetic (E = 1 keV to 3 MeV) electron flux at ionospheric altitudes over L-shells ranging 1.8 to 4.0. These signatures are then extrapolated over longitude and interpolated over latitude to develop the full temporal and spatial precipitation footprints or "hotspots" which form over extensive geographic regions, subject to a selectable minimum precipitation energy threshold (E > Eth);Results indicate a universal poleward displacement of the peak precipitation flux by ∼ 15° with respect to the latitude of the causative lightning source, owing to the general tendency of the oblique waves to propagate across magnetic field lines (initially from lower to higher L-shells) so that the most intense whistler waves which originate directly above the lightning discharge subsequently arrive near the magnetic equator (where the strongest scattering takes place) at L-shells which are higher than the L-shell passing through the source.;Results are summarized in the form of longitude-integrated profiles giving precipitation energy flux vs. latitude and precipitated electron number flux vs. L-shell, both of which show a strong bias in effect towards higher latitudes and L-shells respectively, suggesting that precipitation induced by lightning-generated whistlers on a global-scale is a significant, previously overlooked energetic electron loss mechanism, particularly over the range 2.5≤L≤4 .