Observation of ionospheric irregularities during HF heating at Arecibo

Abstract:

The effects of high-frequency (HF) radio waves on the ionosphere during the 11–15 June 2019 heating campaign at Arecibo Observatory will be presented. The Arecibo Incoherent Scatter Radar (ISR) observed backscatter power irregularities in both the incoherent scatter ion line and plasma line data. The ISR operated in a 20-second cycle of heater-on and heater-off times, allowing for collection of power profiles that are free of HF-induced enhanced ion (HFIL) and plasma line (HFPL) returns. Among other effects, a deep cavity in the power returns was seen near 350 km at 2.7 UT (10.7 AST) on 14 June, corresponding to a depletion in the electron density and a simultaneous enhancement in the electron and ion temperatures. Smaller-intensity irregularities were seen earlier in the experiment as well. We will report on the details of these observations.