Review status: this discussion paper is a preprint. It has been under review for the journal Annales Geophysicae (ANGEO). The manuscript was not accepted for further review after discussion.
Variation in altitude of high-frequency enhanced plasma line by the pump near the 5th electron gyro-harmonic
Jun Wu1,Jian Wu1,Michael T. Rietveld2,Ingemar Haggstrom3,Haisheng Zhao1,Tong Xu1,and Zhengwen Xu1Jun Wu et al.Jun Wu1,Jian Wu1,Michael T. Rietveld2,Ingemar Haggstrom3,Haisheng Zhao1,Tong Xu1,and Zhengwen Xu1
Received: 19 Feb 2019 – Accepted for review: 13 Mar 2019 – Discussion started: 14 Mar 2019
Abstract. During an ionospheric heating campaign carried out at the European Incoherent Scatter Scientific Association (EISCAT), the ultra high frequency incoherent scatter (IS) radar observed a systematic variation in the altitude of the high-frequency enhanced plasma line (HFPL), which behaves depending on the pump frequency. Specifically, the HFPL altitude becomes lower when the pump lies above the 5th gyro-harmonic. The analysis shows that the enhanced electron temperature plays a decisive role in the descent in the HFPL altitude. That is, on the traveling path of the enhanced Langmuir wave, the enhanced electron temperature can only be matched by the low electron density at a lower altitude so that the Bragg condition can be satisfied, as expected from the dispersion relation of Langmuir wave.