Observations of HF-induced instability in the auroral E region

• Published in: Annales Geophysicae
• Main Authors: Schlatter, Nicola M., Ivchenko, Nickolay, Gustavsson, Björn Johan, Leyser, Thomas, Rietveld, Michael T
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus 2013
• Subjects: VDP::Mathematics and natural science: 400::Physics: 430::Space and plasma physics: 437; VDP::Matematikk og Naturvitenskap: 400::Fysikk: 430::Rom- og plasmafysikk: 437; Tromsø; EISCAT
• Online Access: https://hdl.handle.net/10037/6044; https://doi.org/10.5194/angeo-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.