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Reexamining X ‐mode suppression and fine structure in artificial E region field‐aligned plasma density irregularities
Author(s) -
Miceli R. J.,
Hysell D. L.,
Munk J.,
McCarrick M.,
Huba J. D.
Publication year - 2013
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1002/rds.20054
Subject(s) - ionosphere , f region , plasma , physics , computational physics , radar , mode (computer interface) , instability , electric field , atomic physics , optics , geophysics , mechanics , nuclear physics , telecommunications , quantum mechanics , computer science , operating system
Artificial field‐aligned plasma density irregularities (FAIs) were generated in the E region of the ionosphere above the High Frequency Active Auroral Research Program facility during campaigns in May and August of 2012 and observed using a 30 MHz coherent scatter radar imager in Homer, Alaska. The purpose of this ionospheric modification experiment was to measure the threshold pump power required to excite thermal parametric instabilities by O ‐mode heating and to investigate the suppression of the FAIs by simultaneous X ‐mode heating. We find that the threshold pump power for irregularity excitation was consistent with theoretical predictions and increased by approximately a factor of 2 when X ‐mode heating was present. A modified version of the Another Model of the Ionosphere (SAMI2) ionospheric model was used to simulate the threshold experiments and suggested that the increase was entirely due to enhanced D region absorption associated with X ‐mode heating. Additionally, a remarkable degree of fine structure possibly caused by natural gradient drift instability in the heater‐modified volume was observed in experiments performed during geomagnetically active conditions.