Bibliography

Model of the E-Layer Critical Frequency for the Auroral Region

A new foE model for the auroral region is constructed; the model is based on an analysis of the models of auroral electron precipitations, the boundaries of the discrete and diffusive aurora, the main ionospheric trough, and measurements of the E-layer critical frequency foE. The model is an analytical model. It consists of solar (foEsol) and auroral (foEavr) components. The solar component of the model does not depend of geomagnetic activity. It depends on solar activity via the F index, which is determined by the solar radio emission flux at a wavelength of 10.7 cm over the previous day and three solar rotations. The auroral component of the model does not depend of solar activity. It depends on geomagnetic activity via the effective Kp* index, which takes into account the prehistory of changes in this activity. The model indirectly takes into account the dependence of the relative contribution of  foEsol and  foEavr to the total  foE value on the difference in the heights of the maxima of these model components via the addition of a coefficient. The model qualitatively takes into account the effect of the winter anomaly in foEavr via the addition of a function. It is found that the errors of the new foE model in the auroral region at the nighttime hours are much lower than those in the international IRI model (with the STORM-E option) for both moderate and high geomagnetic activity. For example, the comparison with data from ionospheric stations shows that the IRI model underestimates foE in these conditions by approximately a factor of 2 on average. The average shift in foE relative to the experimental data in the new model does not exceed 20\%.

Deminov, M.; Shubin, V.; Badin, V.;

Published by: Geomagnetism and Aeronomy      Published on: sep

YEAR: 2021     DOI: 10.1134/S0016793221050054

Winter anomaly of the E-layer critical frequency in the nighttime auroral zone

Analysis of the annual variation of the E-layer critical frequency median foE in the nighttime (22-02 LT) auroral zone by the data of several stations of the Northern Hemisphere has shown the median maximum in winter and minimum in summer, even though the summer contribution of solar radiation to foE is greater. Thus, a new phenomenon was discovered\textemdashan foE median winter anomaly in the nighttime auroral zone. Its amplitude (ratio of winter to summer foE figures) can reach 10\textendash15\%; however, this anomaly was weakly expressed and statistically insignificant at particular stations located in the auroral zone. The winter anomaly is more distinct for foE _avr, the median of the E-layer critical frequency foE caused by the auroral source of atmospheric ionization, i.e., excluding the solar radiation contribution to foE. For foE _avr, the amplitude of the winter anomaly can reach 15\textendash20\%. Based on the qualitative analysis, it has been found that foE winter anomaly is stipulated by the winter/summer asymmetry of energy flow of accelerated electrons, which induce discrete aurorae in the nighttime auroral zone.

Deminov, M.; Deminova, G.;

Published by: Geomagnetism and Aeronomy      Published on: 10/2017

YEAR: 2017     DOI: 10.1134/S0016793217050061

Winter anomaly of the E-layer critical frequency in the nighttime auroral zone

Analysis of the annual variation of the E-layer critical frequency median foE in the nighttime (22-02 LT) auroral zone by the data of several stations of the Northern Hemisphere has shown the median maximum in winter and minimum in summer, even though the summer contribution of solar radiation to foE is greater. Thus, a new phenomenon was discovered\textemdashan foE median winter anomaly in the nighttime auroral zone. Its amplitude (ratio of winter to summer foE figures) can reach 10\textendash15\%; however, this anomaly was weakly expressed and statistically insignificant at particular stations located in the auroral zone. The winter anomaly is more distinct for foE _avr, the median of the E-layer critical frequency foE caused by the auroral source of atmospheric ionization, i.e., excluding the solar radiation contribution to foE. For foE _avr, the amplitude of the winter anomaly can reach 15\textendash20\%. Based on the qualitative analysis, it has been found that foE winter anomaly is stipulated by the winter/summer asymmetry of energy flow of accelerated electrons, which induce discrete aurorae in the nighttime auroral zone.

Deminov, M.; Deminova, G.;

Published by: Geomagnetism and Aeronomy      Published on: 10/2017

YEAR: 2017     DOI: 10.1134/S0016793217050061