Open AccessELF-VLF atmospheric waveforms under night-time ionospheric conditions
Author(s) -
A. I. Sukhorukov
Publication year - 1996
Publication title -
annales geophysicae
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.522
H-Index - 93
eISSN - 1432-0576
pISSN - 0992-7689
DOI - 10.1007/s00585-996-0033-7
Subject(s) - ionosphere , atmospherics , amplitude , computational physics , waveform , physics , atmospheric electricity , very low frequency , waveguide , lightning (connector) , geophysics , anisotropy , earth–ionosphere waveguide , local time , geology , meteorology , optics , ionospheric absorption , electric field , mathematics , power (physics) , quantum mechanics , voltage , astronomy , statistics
Tweek atmospherics generated by lightning\uddischarges and propagated in the night-time Earth-ionosphere waveguide, have\udoften very pronounced dispersive features near the first few waveguide cut-off\udfrequencies ( fcm~m\dot{s} fc1,\udfc 1~1.6–1.9 kHz, m=1, 2, . . . , ),\udbeing very extended in time, and have rather large amplitudes of oscillations\udwith periods corresponding to the narrow vicinity of the cut-off frequencies. In\udthis paper an analytical approach is developed to describe the waveform of\uddistant tweeks. It is based on the solving of the Maxwell equations in two\udqualitatively different regions, whose changes are related in the first instance\udto the changes in the relative magnitudes of the displacement current and\udcomponents of the conduction currents, and the following asymptotic matching of\udthe solutions in the transitional region. The analytical night-time waveguide\udmodel accounts for both anisotropy and vertical inhomogeneity of the low\udionosphere. The model is valid for upper ELF – lower VLF range and is well\udsuitable for the analysis of the QTEm modes in the cut-off\udfrequency regions, which determine the most important part of the tweek spectra\udand tweek amplitudes. The influence of the different ionospheric heights on the\udtweek characteristics is determined. The efficiency of the tweek generation by\udcloud-to-cloud discharge is also evaluated