V. L. Frolov

Auroral activity caused by high-power radioemission from the SURA facility

A series of experimental modifications of the ionosphere in the HF range, performed at the SURA facility base, together with optical measurements onboard the International Space Station (ISS), indicated that such impacts on the ionosphere are effective when the facility operational frequency is higher than the critical plasma frequency (for the main ionospheric F2 layer). The experimental measurements were supported by measurements at ground-based observatories, ISS, and the Demeter and GPS satellites. The analysis results of the entire data set are presented. The ray HF radio tracing for the experiment of October 2, 2007, has been calculated, and it has been indicated that the ionosphere to the north of the facility up to 60°–62° N latitudes was irradiated by the facility beam (the effects of ray redistribution and refocusing) due to refraction on the gradient of the F2 layer critical frequencies. An analysis of the ground-based and satellite measurements (both in the vicinity of a heater and in the magnetically conjugate region) indicates that it is possible to trigger a substorm in experiments with the Sura heating facility.

Response of mesospheric ozone to the heating of the lower ionosphere by high-power HF radio emission

We detected a decrease in the intensity of microwave radiation at the atmospheric ozone line at a frequency of 110836.04 MHz during ionospheric modification by high-power HF radiowaves radiated by the Sura Ionospheric Heating Facility. The obtained experimental data allowed us to hypothesize that this effect was caused by the fact that mesospheric ozone was affected by internal gravity waves generated in the E region of the ionosphere during its high-power HF radiowave heating.

Sura Heating Facility Transmissions to the CASSIOPE/e-POP Satellite

Throughout a night-time pass of the CASSIOPE satellite at an altitude of about 1300u2009km above the Sura Heating Facility, transmission of O-mode radiation from Sura to the ePOP Radio Receiver Instrument on CASSIOPE was maintained. Also during this pass, continuous VHF/UHF transmission from the ePOP CERTO radio beacon to three coordinated ground receivers in the Sura vicinity was achieved. Tomography of the VHF/UHF received wave data based on total electron content permitted the two-dimensional distribution of ionospheric ambient electron plasma frequency fpe to be determined in the latitude-altitude space between Sura and CASSIOPE. foF2 values about 0.1u2009MHz above the Sura pump frequency of 4.3u2009MHz were measured by the tomography. We examine the question of whether the observations can be explained on the basis of classic propagation in a smooth ionosphere. Tracing of rays from Sura towards CASSIOPE orbital locations finds most rays reflected away from the topside by the patchy ionospheric structure in bottomside fpe. It is concluded that O-mode ducting in under-dense field-aligned irregularities is responsible for maintaining the transionospheric transmission across the 2-min pass. O-to-Z mode “radio-window” conversion in the F-region bottomside is not required to explain these data.

Influence of an artificially disturbed ionosphere on the mesospheric ozone

The results of microwave measurements of ozone emission in the middle atmosphere during modification of the ionosphere by high-power short radio waves on March 14–19, 2009 and on March 27–28, 2011. The modification was carried out using a SURA heating facility (Radiophysical Research Institute) in conjunction with two microwave ozonometers aimed at different parts of the sky. A new physical phenomenon of decrease of the intensity of microwave emission from the mesosphere in the ozone line upon the modification of the ionosphere with high-power short radio waves is discovered.

New phenomenon observed on board the ISS during a RF ionosphere modification.

A quantitative analysis is presented of the data on modification of the ionosphere by high-power radio emission from the SURA heating experiment run on October 2, 2007 (18:40 – 19:00 UT). The Sura facility was working in the mode of periodic heating at the radio frequency (RF) of 4.30 MHz. The modulation frequency was close to the frequency of natural Alfven oscillations of plasma in the local magnetic flux tube. The effects of modification were observed onboard the Russian Segment of the International Space Station (RS ISS). The observations have provided more than 1500 images of a bright local glow, which appeared within the field of view of the TV camera as the ISS was passing close to the location of the Sura facility. The brightness of aurora reached some hundreds of kiloRayleighs. The compact bright aurora appeared North-East of the heating facility and was moving East in the image plane. The analysis of helio-geophysical conditions did not reveal any significant anomalies during the experiment. A low power of the heating RF emission and high intensity of the observed aurora suggest that the local glow wasnt due directly to HF heating of ionosphere, but rather might be caused by the particle precipitation artificially stimulated by the heating effects, such as modification of the ionosphere over the SURA heating facility, which forms the base of the magnetic flux tube (and the standing wave node) whose natural Alfven oscillations have a period close to the modulation period of the heating HF emission. The Alfven mode of the magnetic tube could be intensified during the experiment by a short (less than 1 min) and weak (amplitude of about 2 nT) pulse in the planetary geomagnetic field that occurred at 18:47:30 UT.