Ion cyclotron harmonics in auroral radar echoes: Real effect or analysis artifact?

Certain analyses of Canadian radar studies of auroral electrojet echoes have apparently shown spectra with multiple ion cyclotron harmonic peaks. On the basis of these, it has been argued that ion cyclotron effects must be important for all echo types seen by VHF radars, not just type 3. We reject t...

Ausführliche Beschreibung

Gespeichert in:
Bibliographische Detailangaben
Veröffentlicht in:Geophysical research letters 1991-04, Vol.18 (4), p.709-712
Hauptverfasser: Farley, D. T., Sahr, J. D., Providakes, J. F.
Format: Artikel
Sprache:eng
Schlagworte:
Online-Zugang:Volltext
Tags: Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
Beschreibung
Zusammenfassung:Certain analyses of Canadian radar studies of auroral electrojet echoes have apparently shown spectra with multiple ion cyclotron harmonic peaks. On the basis of these, it has been argued that ion cyclotron effects must be important for all echo types seen by VHF radars, not just type 3. We reject this conclusion for two reasons: (1) at the altitude of auroral backscatter (∼ 100–120 km) the ion‐neutral collision frequency is much higher than the gyro frequency—ions are essentially unmagnetized; (2) we show that the “high resolution” signal processing algorithm employed does not distinguish between echoes with and without harmonic structure. With a simulation, we show that the algorithm itself can impose apparent quasi harmonic structure onto the spectrum of random noise.
ISSN:0094-8276
1944-8007
DOI:10.1029/91GL00122