Reexamining X‐mode suppression and fine structure in artificial E region field‐aligned plasma density irregularities. Issue 5 (5th September 2013)

• Record Type: Journal Article
• Authors: Miceli, R. J.; Hysell, D. L.; Munk, J.; McCarrick, M.; Huba, J. D.
• Is Part Of: Radio science. Volume 48:Issue 5(2013:Oct.)
• Page Start: 482
• Page End: 490
• Publication Date: 2013-09-05
• Subjects: Radio meteorology -- Periodicals; Radio wave propagation -- Periodicals; 621.38405
• DOI: 10.1002/rds.20054
• Languages: English
• ISSNs: 0048-6604

Abstract

<abstract abstract-type="main" id="rds20054-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p id="rds20054-para-0001">[1] Artificial field‐aligned plasma density irregularities (FAIs) were generated in the <italic>E</italic> 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 <italic>O</italic>‐mode heating and to investigate the suppression of the FAIs by simultaneous <italic>X</italic>‐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 <italic>X</italic>‐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 <italic>D</italic> region absorption associated with <italic>X</italic>‐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.</p> </abstract>