Simultaneous ground‐ and satellite‐based observation of MF/HF auroral radio emissions

• Published in: Journal of geophysical research. Space physics 2016-05, Vol.121 (5), p.4530-4541
• Main Authors: Sato, Yuka, Kumamoto, Atsushi, Katoh, Yuto, Shinbori, Atsuki, Kadokura, Akira, Ogawa, Yasunobu
• Format: Article
• Language: English
• Subjects: Altitude; Auroral electrons; auroral radio emissions; Auroral zones; Biomedical materials; Detectors; E region; Emission measurements; Emissions; F region; Ground level; Ground stations; Ground-based observation; High frequencies; Ionization; Ionospheric absorption; mode conversion; Plasma waves; Radiation; Radio astronomy; Radio emission; Satellite observation; Satellite-borne instruments; Satellites; Solar ultraviolet radiation; Stations; Surgical implants; Ultraviolet radiation; upper hybrid waves
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1002/2015JA022101

We report on the first simultaneous measurements of medium‐high frequency (MF/HF) auroral radio emissions (above 1 MHz) by ground‐ and satellite‐based instruments. Observational data were obtained by the ground‐based passive receivers in Iceland and Svalbard, and by the Plasma Waves and Sounder experiment (PWS) mounted on the Akebono satellite. We observed two simultaneous appearance events, during which the frequencies of the auroral roar and MF bursts detected at ground level were different from those of the terrestrial hectometric radiation (THR) observed by the Akebono satellite passing over the ground‐based stations. This frequency difference confirms that auroral roar and THR are generated at different altitudes across the F peak. We did not observe any simultaneous observations that indicated an identical generation region of auroral roar and THR. In most cases, MF/HF auroral radio emissions were observed only by the ground‐based detector, or by the satellite‐based detector, even when the satellite was passing directly over the ground‐based stations. A higher detection rate was observed from space than from ground level. This can primarily be explained in terms of the idea that the Akebono satellite can detect THR emissions coming from a wider region, and because a considerable portion of auroral radio emissions generated in the bottomside F region are masked by ionospheric absorption and screening in the D/E regions associated with ionization which results from auroral electrons and solar UV radiation. Key Points First simultaneous space/ground‐based observation of >1 MHz auroral radio emissions Frequency differences corroborate different source altitudes across the F peak Space‐ and ground‐level detections do not always accompany one another