Critical frequencies of the ionospheric F1 and F2 layers during the last four solar cycles: Sunspot group type dependencies. (June 2018)

• Record Type: Journal Article
• Authors: Yiğit, Erdal; Kilcik, Ali; Elias, Ana Georgina; Dönmez, Burçin; Ozguc, Atila; Yurchshyn, Vasyl; Rozelot, Jean-Pierre
• Is Part Of: Journal of atmospheric and solar-terrestrial physics. Volume 171(2018)
• Page Start: 157
• Page End: 163
• Publication Date: 2018-06
• Subjects: Ionosphere -- Sunspots -- Ionospheric critical frequencies -- Solar cycle; Geophysics -- Periodicals; Atmospheric physics -- Periodicals; Géophysique -- Périodiques; Météorologie physique -- Périodiques; Electronic journals; 551.51
• DOI: 10.1016/j.jastp.2017.11.018
• Languages: English
• ISSNs: 1364-6826

Abstract

Abstract: The long term solar activity dependencies of ionospheric F1 and F2 regions' critical frequencies ( f 0 F 1 and f 0 F 2 ) are analyzed for the last four solar cycles (1976–2015). We show that the ionospheric F1 and F2 regions have different solar activity dependencies in terms of the sunspot group (SG) numbers: F1 region critical frequency ( f 0 F 1 ) peaks at the same time with the small SG numbers, while the f 0 F 2 reaches its maximum at the same time with the large SG numbers, especially during the solar cycle 23. The observed differences in the sensitivity of ionospheric critical frequencies to sunspot group (SG) numbers provide a new insight into the solar activity effects on the ionosphere and space weather. While the F1 layer is influenced by the slow solar wind, which is largely associated with small SGs, the ionospheric F2 layer is more sensitive to Coronal Mass Ejections (CMEs) and fast solar winds, which are mainly produced by large SGs and coronal holes. The SG numbers maximize during of peak of the solar cycle and the number of coronal holes peaks during the sunspot declining phase. During solar minimum there are relatively less large SGs, hence reduced CME and flare activity. These results provide a new perspective for assessing how the different regions of the ionosphere respond to space weather effects. Highlights: Dependencies of Ionospheric critical frequencies to different sunspot groups. Observed anomalous behaviors in ionospheric critical frequencies and solar activity during solar cycle 23. FoF1 is more sensitive to slow solar wind; FoF2 is more sensitive to fast solar winds and CMEs.