Artificial periodic irregularities, wave phenomena in the lower ionosphere, and the sporadic E layer

Abstract

We present new results of studying the artificial periodic irregularities produced in the ionosphere by the radio emission of the high-power heating facility "Sura" during the period of observations of the sporadic E layer. Basing on the measurement results for the velocity of the vertical plasma motion and the electron profile density in the E region of the ionosphere, which were obtained by the method of resonance scattering of radiowaves by an artificially produced periodic structure, we analyze the possibility to produce a sporadic E layer by driving metal ions affected by the vertical shear of the velocity, which occurs at these altitudes due to the propagation of internal gravity waves. The parameters of these waves are evaluated, as well as the mass and concentration of metal ions in the sporadic E layer.

Artificial periodic irregularities in the high‐latitude ionosphere excited by the HAARP facility

“…[] reported that decay times varied from a few milliseconds at the upper height (up to 140 km) for the few second at the lowest (80–90 km). Numerous API observations in D and E regions at Sura show the decay time of the same order as at HAARP [ Bakhmetieva and Belikovich , 2008; Bakhmetieva et al , , ]. Usually, APIs in the D and E regions existed throughout all experiments at the midlatitudes and show high variability of the echo amplitude at all heights.…”

“…[, , ]. The most recent experiments on the API formation were carried out using similar pumping and probing waves [ Bakhmet ' eva et al ., , , ; Bakhmetieva and Belikovich , , ; Grigoriev et al ., ; Tolmacheva et al ., ].…”

“…The maximum of amplitude of the API scattered signal corresponds to the height of the maximum of the E region. In the left plot of Figure prior API generation sporadic E layer is not available, but API technique allows to detect very weak sporadic layers [ Belikovich et al ., ; Kagan et al ., ; Bakhmet ' eva et al ., ].…”

“…[], Bakhmetieva and Belikovich [], and Bakhmet'eva et al . []. Effect of sporadic E layer on the APIs is manifested by the local growth of the signal amplitude by as high as 30–40 dB at the altitudes of E s layer.…”

“…It should be noted that using the API technique, we can detect sporadic layers in the lower ionosphere including very weak sporadic ionization layers with an electron density lower than 10 4 cm −3 , which cannot be recorded by a conventional ionosonde [ Kagan et al ., ; Bakhmetieva and Belikovich , , ; Bakhmet ' eva et al ., ].…”