Oblique noise bands above local LHR frequency Original Research Article

The noise bands at lower hybrid resonance (LHR) frequency at a satellite position have already been observed and described. Observations onboard the MAGION 5 satellite revealed oblique noise bands above the local LHR frequency. Examples of such oblique bands, both in review (large time-scale) spectrograms, and in detailed (small time-scale) spectrograms are presented. Based on ray-tracing simulations, an explanation of these oblique bands is suggested. We show that they are formed due to the separation of nonducted whistler mode waves of different frequencies propagating near the so-called resonance cone. The influence of plasmaspheric disturbances upon these emissions is also discussed. We suggest that oblique noise bands are mainly formed under quiet conditions, when indistinct plasmapause is situated at higher L shells.