Observations of HF-induced instability in the auroral E region

• Published in: Annales Geophysicae
• Main Authors: Schlatter, N. M., Ivchenko, N., Gustavsson, B., Leyser, T., Rietveld, M.
• Format: Text
• Language: English
• Published: 2018
• Subjects: Tromsø; EISCAT
• Online Access: https://doi.org/10.5194/angeo-31-1103-2013; https://angeo.copernicus.org/articles/31/1103/2013/

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.