Midlatitude ionospheric changes to four great geomagnetic storms of solar cycle 23 in Southern and Northern Hemispheres

Abstract

This paper presents an investigation of ionospheric response to great (Dst<=\textendash350 nT) geomagnetic storms that occurred during solar cycle 23. The storm periods analyzed are 29 March to 2 April 2001, 27\textendash31 October 2003, 18\textendash23 November 2003, and 6\textendash11 November 2004. Global Navigation Satellite System, total electron content (TEC), and ionosonde critical frequency of F 2 layer (f o F 2 ) data over Southern Hemisphere (African sector) and Northern Hemisphere (European sector) midlatitudes were used to study the ionospheric responses within 15\textdegreeE\textendash40\textdegreeE longitude and \textpm 31\textdegree to \textpm 46\textdegree geomagnetic latitude. Midlatitude regions within the same longitude sector in both hemispheres were selected in order to assess the contribution of the low-latitude changes especially the expansion of equatorial ionization anomaly (EIA) also called the dayside ionospheric superfountain effect during these storms. In all storm periods, both negative and positive ionospheric responses were observed in both hemispheres. Negative ionospheric responses were mainly due to changes in neutral composition, while the expansion of the EIA led to pronounced positive storm effects at midlatitudes for some storm periods. In other cases (e.g., 29 October 2003), penetration electric fields, EIA expansion, and large-scale traveling ionospheric disturbances were found to be present during the positive storm effect at midlatitudes in both hemispheres. An increase in TEC on the 28 October 2003 was because of the large solar flare with previously determined intensity of X45 \textpm 5.

Year of Publication
2016
Journal
Space Weather
Volume
14
Number of Pages
1155-1171
Date Published
12/2016
URL
https://ieeexplore.ieee.org/abstract/document/7894429
DOI
10.1002/swe.v14.1210.1002/2016SW001516
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