This article has an erratum: [https://doi.org/10.1051/swsc/2022013]
J. Space Weather Space Clim.
Volume 12, 2022
Topical Issue - Ionospheric plasma irregularities and their impact on radio systems
|Number of page(s)||21|
|Published online||13 April 2022|
Interhemispheric variability of the electron density and derived parameters by the Swarm satellites during different solar activity
Department of Physics, University of Oslo, Box 1048 Blindern, 0316 Oslo, Norway
* Corresponding author: firstname.lastname@example.org
Accepted: 6 March 2022
With the data from the Swarm satellite mission, we study the variability of ionospheric plasma parameters for low and high solar activities. We focus on the electron density measured by Swarm and derived parameters and analyze the variability of these parameters in the contexts of the Northern and Southern hemispheres, specific latitudinal regions, and the solar activity level. We consider two time intervals: with high solar activity (HSA) from August 2014 to July 2015 and with low solar activity (LSA) from January to December 2018. We show that the electron density is described mainly by three probability density functions (PDF): exponentiated Weibull, lognormal, and chi distributions. These results with PDFs can be applied to the modeling or prediction of ionospheric parameters in different regions. The best fit of PDFs was obtained for low and mid-latitudes, while at high latitudes and in the polar caps, the double-peaked features of the distribution require the fit of multiple PDFs. The electron density (Ne) distribution at low latitudes follows more a lognormal distribution, while in the high latitude region, the chi distribution prevails. Different results were obtained for the rate of change of density index (RODI) with two fitting PDFs: lognormal or exponentiated Weibull, where the best fits are for high latitudes and polar caps. We demonstrate high variability in the electron density and derived parameters at low latitudes and in the polar caps. Comparing both hemispheres, we obtained higher values of these parameters during the solar minimum in the Southern hemisphere at high latitudes and polar caps, while for the Northern hemisphere, higher values were obtained at low latitudes. The dependence on the satellite’s altitude was also considered. The main patterns in the diurnal variation of parameters in different regions do not depend on the level of solar activity (which affects only the maximum values). The largest asymmetry between both hemispheres in Ne diurnal distribution was obtained for the polar cap regions. Here a 50% decrease in Ne was observed in the Northern hemisphere during HSA in the early morning sector (04–07 Magnetic Local Time), which has not yet been observed in the Southern hemisphere. For the first time, such a global statistical characterization of the ionospheric plasma density based on the in situ data is presented.
Key words: global statistical study / variability of electron density / symmetry and asymmetry Northern and Southern hemispheres / probability density functions of Ne / diurnal variation of ionosphere
© D. Kotova et al., Published by EDP Sciences 2022
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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