HR: 0830h
AN: SM51C-0556    [PDF]
TI: Simulation study on how electron and proton whistlers appear for different latitudes
AU: * Kim, E
EM: ehkim@khu.ac.kr
AF: Department of Astronomy and Space Science, Kyung Hee University, Yongin, Kyunggi, 449-701 Korea, Republic of
AU: Lee, D
EM: dhlee@khu.ac.kr
AF: Department of Astronomy and Space Science, Kyung Hee University, Yongin, Kyunggi, 449-701 Korea, Republic of
AB: Electron whistlers frequently excite proton whistlers. The proton whistlers appear on the dynamic spectrum as rising tones, which start after the reception of a short electron whistler, asymptotically approaching the local proton gyro-frequency. The proton whistlers are dispersed forms of lightning impulses and their dispersion can be explained by the effects of ions such as ${\rm H^+}$ and ${\rm He^+}$ on the propagation of an electromagnetic wave in the ionosphere. A wave propagating in the ionosphere changes polarization at the altitude where the frequency is close to a cross-over frequency. This polarization reversal provides the mechanism by which an upgoing electron whistler can become a proton whistler. By adopting the multi-fluid numerical wave model, we investigate how the location of the lightning sources affects the electron and proton whistlers. The time histories of electric fields and the dynamic spectra are presented. We show that the polarization reversal occurs at mid- and low-latitudes where the geomagnetic field makes a large angle relative to vertical, while no polarization reversal occurs at high latitudes where the geomagnetic field is nearly vertical. We discuss how electron whistlers disappear when the frequency lies between the crossover frequency and the cutoff frequency in cold plasmas. We also compare our results with the previous theoretical and observational studies.
DE: 2400 IONOSPHERE
DE: 2487 Wave propagation (6934)
DE: 7800 SPACE PLASMA PHYSICS
DE: 7843 Numerical simulation studies
DE: 7868 Wave/wave interactions
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting