Dependence of annual asymmetry in <i>NmF2</i> on local time

Shubin, Valentin

doi:10.31857/S0016794024010091

PII

10.31857/S0016794024010091-1

DOI

10.31857/S0016794024010091

Publication type

Article

Status

Published

Authors

Valentin Shubin

Affiliation: Kazan Federal University

Volume/ Edition

Volume 64 / Issue number 1

Pages

93-100

Abstract

Based on the global empirical model of the F2 layer critical frequency median (Satellite and Digisonde Data Model of the F2 layer, SDMF2), an analysis was made of the properties of diurnal variations in the annual asymmetry in the concentration of the F2 layer maximum NmF2 at different values of the solar activity index F. The AI index, which characterizes the relative difference in NmF2 averaged over all longitudes and latitudes between January and July at a given local time, was used as a parameter of this asymmetry. It was found that the diurnal variations of the AI index are dominated by a semidiurnal mode with maxima in the daytime and at night. The daytime maximum of the AI index is almost independent of the level of solar activity. The nighttime AI maximum decreases with increasing solar activity. For low solar activity, the daytime and nighttime AI maxima almost coincide in amplitude when AI = 16—17%. The difference in the solar radio flux between January and July due to the ellipticity of the Earth’s orbit relative to the Sun makes a significant contribution to the AI index at all hours of the day. On average, it is 3—4% and can reach 5% with low solar activity at night. The difference in the AI index for low and high activity according to the IRI model (with URSI and, especially, CCIR coefficients) is overestimated relative to the SDMF2 model at almost all hours of the day, apparently due to the limited number of experimental data when obtaining the CCIR and URSI coefficients especially over the oceans

Keywords

Date of publication

15.02.2024

Year of publication

2024

Number of purchasers

Views

References

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GOST	Shubin V. Dependence of annual asymmetry in NmF2 on local time // Geomagnetism and Aeronomy. – 2024. – V. 64. – Issue number 1 C. 93-100 . URL: https://geoaeroras.ru/10-31857-s0016794024010091-1/?version_id=109466. DOI: 10.31857/S0016794024010091
MLA	Shubin, Valentin "Dependence of annual asymmetry in NmF2 on local time." Geomagnetism and Aeronomy. 64.1 (2024).:93-100. DOI: 10.31857/S0016794024010091
APA	Shubin V. (2024). Dependence of annual asymmetry in NmF2 on local time. Geomagnetism and Aeronomy. vol. 64, no. 1, pp.93-100 DOI: 10.31857/S0016794024010091

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