Correlational Analysis of the ELF – VLF Nighttime Atmospherics Parameters

Tweek-atmospherics (tweeks), along with radio transmission by VLF stations, are used to study the lower ionosphere. Electromagnetic pulse radiation, which has been excited lightning discharges, a maximum spectral density at extra low frequencies range (ELF, 300...3000 Hz) and very (VLF, 3...30 kHz). The Earth-ionosphere cavity serves as waveguide for electromagnetic waves in these frequency ranges. On spectrogram of tweek, initial part is linearly polarized broadband signal, then number individual harmonics observed. Their instantaneous decrease, asymptotically approaching approximately multiples cutoff waveguide. single position method location estimation ELF wave’s reflection heights ionosphere tweeks implemented into computational algorithm. clusters same azimuths distances sources have obtained during night identified upon ensemble tweek-atmospheric records. data were accumulated Ukrainian Antarctic Station "Akademik Vernadsky" 2019. receiving complex near-polar region makes it possible register tweek two world thunderstorm centers geographic from –60° 130°. results processing studying correlation matrix partial coefficients identify causal relationships between three main parameters such (1) average azimuth arrival regard magnetic meridian, (2) distance center cluster (lightning discharges), (3) harmonics. analysis was applied groups 2.2...7.5 Mm 7.6...9.5 detail. It shown that difference east 0.624 (for entire distances), 0.696 far sources) 0.595 middle range), so, they always exceed values 0.1% significance level. spectrum source 2.2…7.5 be comparable magnitude or azimuth. elimination this masking effect calculating made reveal dependences spectra if propagates outside geomagnetic equator. Thus, non-reciprocity propagation – meridian west directions found tweek-atmospherics. an increased probability detecting higher their close east. also effect, result attenuation radiation weakened east, leads highly significant (with level more than 99.9%) lengths paths station.