Abstract
Abstract. Natural enhancements in the backscattered power of incoherent scatter radars up to 5 orders of magnitudes above the thermal backscatter are sometimes observed at high latitudes. Recently observations of enhancements in the backscattered power including a feature at zero Doppler shift have been reported. These enhancements are limited in altitude to tens of kilometers. The zero Doppler shift feature has been interpreted as a signature of electron density cavitation. Enhanced plasma lines during these observations have also been reported. We report on the first EISCAT UHF observations of enhanced backscattered radar power including a zero Doppler shift feature. The enhancements originated from two distinct and intermittent layers at about 200 km altitude. The altitude extent of the enhancements, observed during auroral high-energy electron precipitation, was < 2 km.
Highlights
Incoherent scatter radars (ISR) measure bulk properties of ionospheric plasma predominantly by analysis of the spectral power backscattered from thermal ion acoustic waves
Akbari et al (2012) reported on naturally enhanced ion acoustic lines (NEIAL) observed with the Poker Flat Incoherent Scatter Radar (PFISR) from a limited-altitude region with a zero Doppler shift feature and enhanced plasma lines at two frequencies
Another model recently proposed by Ekeberg et al (2010) describes NEIAL observations from limited-altitude regions with almost flat ion line spectra, i.e. spectrally uniform radar power enhancements, caused by increased incoherent backscatter cross section driven by ionsolitary waves
Summary
Incoherent scatter radars (ISR) measure bulk properties of ionospheric plasma predominantly by analysis of the spectral power backscattered from thermal ion acoustic waves. Akbari et al (2012) reported on NEIALs observed with the PFISR from a limited-altitude region with a zero Doppler shift feature and enhanced plasma lines at two frequencies. 2001; Isham et al, 2012) Another model recently proposed by Ekeberg et al (2010) describes NEIAL observations from limited-altitude regions with almost flat ion line spectra, i.e. spectrally uniform radar power enhancements, caused by increased incoherent backscatter cross section driven by ionsolitary waves.
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