Abstract
Abstract In order to study the generation and propagation processes of MF auroral radio emissions (referred to as auroral roar and MF burst) in the polar ionosphere, an Auroral Radio Spectrograph (ARS) system was installed at Husafell station in Iceland (invariant latitude: 65.3°). Data analysis of man-made transmissions also provides useful information for the ionosphere study as well as an investigation of auroral radio emissions since the propagation character of MF radio waves changes depending on electron-neutral collisions in the bottomside ionosphere. Thus, ionospheric absorption is examined in comparison with the solar zenith angle and auroral phenomena. The results indicate that the ARS data can be used to detect ionization occurring at distant regions. In late 2006, the ARS detected one auroral roar and twoMF bursts, which were identified as left-handed polarized waves. Results of data analysis, including other auroral data and particle spectra observed by the DMSP satellite, suggest that the MF bursts are generated by electrons with an average energy of several keV associated with auroral breakup. On the other hand, the auroral roar is generated as upper hybrid waves by relatively low-energy electrons over the observation site and propagates downward, being converted into L-O mode electromagnetic waves.
Highlights
Auroral roar and Medium-Frequency burst (MF burst) are members of auroral hectometric emissions, which have been detected at the ground-level
Energy-time spectra of precipitating electrons covering the energy range of 30 eV–30 keV obtained by the DMSP F16 within 5 min during 2150:00–2155:00 UT on September 23 corresponding to the MF burst event (a), and 0121:30–0126:30 UT on November 10 corresponding to the auroral roar event (b), when the conjugate footprint of the satellite was passing closest to the Husafell station. (c) and (d) display electron’s average energy along the satellite paths in a geomagnetic coordinate system using magnetic local time versus invariant latitude for the MF burst event and the roar event, respectively
In order to study the generation and propagation processes of the MF auroral radio emissions in the polar ionosphere, the Auroral Radio Spectrograph (ARS) system was installed at the Husafell station in Iceland
Summary
Auroral roar and Medium-Frequency burst (MF burst) are members of auroral hectometric emissions, which have been detected at the ground-level. Within the data analysis of the present dataset, the DMSP satellites follow no conjugate path over the Husafell station simultaneously with the auroral roar and MF burst events detected by the ARS.
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