V. V. Belikovich

Diagnostics of the lower ionosphere by the method of resonance scattering of radio waves

Abstract Results are presented on measurements of lower ionosphere parameters (electron concentration, coefficient of ambipolar diffusion, etc.) by the method of resonance scattering of radio waves by periodic artificial irregularities. The method of resonance scattering is based on the generation of periodic irregularities in the ionospheric plasma by powerful radio emission and investigation of the characteristics of the back scattering of diagnostic radio waves by these irregularities.

Diagnostics of the ionosphere and neutral atmosphere at E-region heights using artificial periodic inhomogeneities

Abstract An overview of studies of the ionospheric E -region using artificial periodic inhomogeneities (API) is presented. Generation of the electron density API is considered theoretically. Methods of measurements of the electron density profile and neutral atmosphere temperature, density and vertical velocity are outlined and illustrated by experimental results. Some suggestions concerning investigations of the atmospheric turbulence using API are presented.

Studies of the ionosphere and neutral atmosphere using artificial periodic inhomogeneities in the ionospheric plasma

This paper is devoted to a ground-based method for diagnostics of the ionosphere and neutral atmosphere. This method uses one of the numerous physical phenomena observed in the ionosphere illuminated by a high-power radio wave, namely, the generation of artificial periodic inhomogeneities. New results on the ionospheric and atmospheric parameter measurements at E region heights are given.

Ionospheric response to the partial solar eclipse of March 29, 2006, according to the observations at Nizhni Novgorod and Murmansk

The results of observations of the solar eclipse ionospheric effects on March 29, 2006, are presented. The observations were conducted using the partial reflection method near Nizhni Novgorod and the vertical sounding method at the automatic ionospheric station near Murmansk. It has been obtained that the electron density at altitudes of 77 and 91 km decreases by a factor of more than 4; in this case the response of the ionosphere at an altitude of 91 km lags behind the eclipse maximum phase on the Earth by approximately 20 min. It has been established that the eclipse in the E and F1 regions of the polar ionosphere causes a change in the electron density by 15–20%. The delay time of this effect varies from 12 to 24 min depending on the altitude. It has been registered that the reflection virtual altitude at altitudes of the ionospheric F region increases in Murmansk and Nizhni Novgorod.

Vertical motions in the lower ionosphere and a sporadicE-layer

We propose a calculation technique for the main characteristics of a sporadic E-layer, including the effective recombination coefficient, the relative content of meteor and atmospheric ions in the layer, and the time of its evolution. This technique is based on measurements of vertical plasma velocities by the method of resonance scattering of radio waves by artificial periodic inhomogeneities of the electron density. The contribution of internal gravity waves and turbulent motions to the formation of sporadic layers is estimated. The characteristic values of the turbulent velocity measured by this method at the heights of the turbopause are presented. The possible mechanisms of mid-latitude sporadic E-layer formation at heights of 90 to 120 km are considered. Experimental studies confirmed the main statements of the wind shear theory concerning the determining role of the redistribution of ionization under the action of atmospheric winds with vertical gradient of velocity in the formation of Es.

Investigation of wave motions in the lower ionosphere by the method of resonance scattering of radio waves from artificial periodic inhomogeneities

We present the results of studies of wave motions at lower-ionosphere altitudes by a new method based on measurements of the velocity of vertical motion of plasma by the variation of the phase of the signal that is backscattered from artificial periodic inhomogeneities of electron density (ionospheric arrays). The method allows us to study processes with different time scales and periods of from several dozens of seconds to some hours or longer. In the course of long-term 1990–1991 observations conducted near Nizhny Novgorod we determined some dynamic and spectral characteristics of internal gravity waves.

Artificial periodic inhomogeneities of the ionosperic plasma as a promising line in the ionospheric research

This paper is dedicated to a new method of ionospheric studies, developed at the Radiophysical Research Institute (NIRFI) and based on the creation of artificial periodic inhomogeneities (APIs) of the ionospheric plasma. We review the techniques and present the results of determination of the basic parameters of the ionosphere and atmosphere.

Studies of the Ionospheric D -Region Using Partial Reflections in Spring 2004 at Middle and High Latitudes

Results of the observations of the ionospheric effects of two solar flares in April 2004 performed using partial reflections are presented. The studies were carried out at the measuring facilities located in different latitudinal regions: at Vasil’sursk station in the Nizhni Novgorod region and at Tumannyi station in the Murmansk region. The quantitative estimates of the electron density in the polar and midlatitude D region under quiet conditions and during solar flares were obtained. The correlation between rapid variations in electron concentration at heights of about 80 km at these stations was found and it was shown that during solar flares the electron density at heights of 60–70 km corresponds to the intensity of the X-ray flux in the range of 0.5–3 Å, which points to the action of the linear law of recombination in the ionospheric D region.

Study of the Twilight D Region of the Ionosphere using Artificial Periodic Inhomogeneities

We analyze the behavior of the ionospheric D region during sunset and sunrise using the results of measurements performed in August 2000 at the “Sura” facility by the method of artificial periodic inhomogeneities. The measured altitude profiles of the relaxation time and the scattered-signal amplitude are interpreted within the framework of a model with single negative-ion species O2-. Variations in the number densities of atomic and excited molecular oxygen and the altitude profiles of the electron density are found.

A study of the winter-time D-region using the partial reflection technique

Abstract The results of observations performed by a partial reflection radar at Gorky (56,1°N, 44,3°E) during the winters of 1982–1983 and 1983–1984 are presented. The following D-region parameters were measured: electron densities for fixed solar zenith angles (1982–1983 χ ~ 78°, 1983–1984 χ ~ 78°, 84°), wind velocities and frequency spectra of scattered signals. On the basis of simultaneous wind and frequency spectrum measurements the horizontal scale of scattering irregularities is estimated.