Radar observations of artificial E-region field-aligned irregularities
| Autor: | Christopher T. Fallen, D. L. Hysell, Brenton Watkins, E. Nossa |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
Physics
Atmospheric Science Daytime business.industry Aeronomy lcsh:QC801-809 Geology Astronomy and Astrophysics Instability lcsh:QC1-999 lcsh:Geophysics. Cosmic physics Optics Amplitude Critical frequency Space and Planetary Science Earth and Planetary Sciences (miscellaneous) lcsh:Q lcsh:Science business Field aligned irregularities lcsh:Physics Zenith Radio wave |
| Zdroj: | Annales Geophysicae, Vol 27, Iss 7, Pp 2699-2710 (2009) Annales Geophysicae, Vol 27, Pp 2699-2710 (2009) |
| ISSN: | 1432-0576 |
| DOI: | 10.5194/angeo-27-2699-2009 |
| Popis: | Artificial E region field aligned plasma density irregularities (FAIs) were generated using HAARP in four different experimental modes and observed with a coherent scatter radar imager located 450 km to the southwest where it could detect field-aligned backscatter. The experiments were conducted in July of 2008, during the Polar Aeronomy and Radio Science Summer School (PARS), during quiet conditions in the daytime when the E layer was dense and absorption was modest. The echoes observed during zenith and magnetic zenith heating experiments were deflected from their nominally anticipated horizontal positions toward the midpoint position. The occurrence of hysteresis when heating with amplitude modulated pulses implied the development of the resonance instability, although the threshold for the onset of instability appeared to be higher than what has been predicted theoretically. Heating experiments involving pump frequencies slightly above and below the second electron gyroharmonic frequency produced no significant differences in the observed echoes. Finally, heating with a pump frequency slightly above the E region critical frequency appears to have produced FAIs at two distinct altitudes where the upper-hybrid resonance condition could be satisfied. |
| Databáze: | OpenAIRE |
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