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Titova et al. 2007
Titova, E.E., Demekhov, A.G., Pasmanik, D.L., Trakhtengerts, V.Y., Manninen, J., Turunen, T. and Rycroft, M.J. (2007). Ground-based observations at L ~ 6 of multi-band structures in VLF hiss. Geophysical Research Letters 34: doi: 10.1029/2006GL028482. issn: 0094-8276.

We present ground-based observations of banded structures (BS) in auroral hiss. This BS hiss was detected at Poroj¿rvi station in Northern Finland, mainly in the local evening from 19 to 23 MLT, during magnetically quiet periods; half of all the events observed corresponded to AE < 50 nT. The structures, which resemble those observed by low-altitude satellites, can be related to the cyclotron resonant interaction of VLF waves at frequencies near the lower-hybrid resonance with suprathermal protons in the upper ionosphere and magnetosphere. The maximum probability distribution of band spacing for the events observed at Poroj¿rvi is reached in the frequency range 200--300 Hz, which corresponds to proton gyrofrequencies at L ~ 6 at altitudes of 4000--3000 km. We found that the BS hiss was detected in the region of evening-side downward field-aligned currents and rather intense precipitation of ions with energies 1--30 keV, detected by DMSP spacecraft. We propose that the observed BS hiss can be formed not only due to absorption at the proton gyroharmonics, as is usually assumed for similar structures observed onboard satellites, but also due to generation by energetic protons with an anisotropic velocity distribution.

BACKGROUND DATA FILES

Abstract

Keywords
Magnetospheric Physics, Plasma waves and instabilities, Magnetospheric Physics, Auroral phenomena, Ionosphere, Wave propagation (0689, 3285, 4275, 4455, 6934), Magnetospheric Physics, Energetic particles, precipitating
Journal
Geophysical Research Letters
http://www.agu.org/journals/gl/
Publisher
American Geophysical Union
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