Observations of HF-induced instability in the auroral E region

• Published in: Annales Geophysicae
• Main Authors: N. M. Schlatter, N. Ivchenko, B. Gustavsson, T. Leyser, M. Rietveld
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2013
• Subjects: Science; Q; Physics; QC1-999; Geophysics. Cosmic physics; QC801-809; Tromsø; EISCAT
• Online Access: https://doi.org/10.5194/angeo-31-1103-2013; https://doaj.org/article/70d5a2b3724a4dc180f2868078ee807f

Enhancements were observed in backscattered radar power during an ionospheric heating experiment from two distinct altitude regions in the auroral E region above Tromsø. For the experiment the EISCAT Tromsø heater was operated with O mode and X mode alternated at 4.04 MHz, close to the 3rd electron gyroharmonic. Ion-line data recorded with the EISCAT UHF radar reveal different temporal evolutions as well as different ion-line characteristics for the enhancements from the two altitude regions. The upper layer is dominated by a strong central feature, whereas the lower layer has three peaks corresponding to the central feature and the two ion lines. The altitude region of the two closely spaced (altitude separation ~ 5 km) but distinct enhancements is close to the critical altitude for the heater wave.