Observations of auroral hiss, LHR noise, and other phenomena in the frequency range 20 Hz-540 kHz on Ogo 6

摘要: The payload of the polar-orbiting Ogo 6 spacecraft includes an experiment with four broadband receivers (0.02–15, 15–30, 92.5–107.5, and 280–295 kHz), two narrowband at 200 540 kHz, a intensity detector. are connected to electric dipole antenna thus respond not only electromagnetic but also electrostatic waves, such as lower hybrid resonance (LHR) noise. LHR noise bands, observed below auroral latitudes in range from few about 20 kHz are, fact, among most intense phenomena by experiment. intensities signals often exceed full-scale reading 3 mv/m usually contained bandwidth kHz. Full-scale readings exceeded hiss, its extends cutoff near frequency highest monitored (540 kHz). spectral shape hiss vary both within event event, typical E field is 1 μv/m/Hz1/2 audio frequencies, decreasing 0.15 0.025 For longitudinal propagation whistler mode index refraction unity, this would yield flux density 6×10−17 w/m2/Hz 1.7×10−18 indicating rapid decrease increasing frequency. Auroral has been high 4.5 (≃5.5×10−14 w/m2/Hz) Under geomagnetically quiet conditions center ‘auroral zone’ 70° invariant magnetic midnight, through 75° 0600 1800 MLT, 78° noon. zone moves on average 5° toward equator under disturbed conditions. In subpolar polar very narrow band low-frequency experiment, suggesting presence dc fields. Intense VLF nearly parallel geomagnetic field. These may result some type interaction between local plasma, they could be related recently detected fluxes trapped low-energy electrons low L values.