Multi-station investigation of spread F over Europe during low to high solar activity

• Published in: Journal of space weather and space climate Vol. 8; p. A27
• Main Authors: Paul, Krishnendu Sekhar, Haralambous, Haris, Oikonomou, Christina, Paul, Ashik, Belehaki, Anna, Ioanna, Tsagouri, Kouba, Daniel, Buresova, Dalia
• Format: Journal Article
• Language: English
• Published: les Ulis EDP Sciences 2018
• Subjects: Dependence; effects of solar activity over spread F occurrence; Electric fields; Equatorial regions; F region; Geomagnetic storms; Geomagnetism; Gravitational waves; Growth rate; Instability; Ionosphere; Ionospheric disturbances; longitudinal and latitudinal dependence of spread F occurrence; Magnetic storms; Morphology; nighttime midlatitude ionosphere over Europe; Plasma; Radar; Solar activity; Solar cycle; Southern Hemisphere; Spread F; Stability; Statistical analysis; Storms; Traveling ionospheric disturbances; Wind
• ISSN: 2115-7251; 2115-7251
• DOI: 10.1051/swsc/2018006

Spread F is an ionospheric phenomenon which has been reported and analyzed extensively over equatorial regions on the basis of the Rayleigh-Taylor (R-T) instability. It has also been investigated over midlatitude regions, mostly over the Southern Hemisphere with its generation attributed to the Perkins instability mechanism. Over midlatitudes it has also been correlated with geomagnetic storms through the excitation of travelling ionospheric disturbances (TIDs) and subsequent F region uplifts. The present study deals with the occurrence rate of nighttime spread F events and their diurnal, seasonal and solar cycle variation observed over three stations in the European longitude sector namely Nicosia (geographic Lat: 35.29 °N, Long: 33.38 °E geographic: geomagnetic Lat: 29.38 °N), Athens (geographic Lat: 37.98 °N, Long: 23.73 °E geographic: geomagnetic Lat: 34.61 °N) and Pruhonice (geographic Lat: 50.05 °N, Long: 14.41 °E geographic: geomagnetic Lat: 47.7 °N) during 2009, 2015 and 2016 encompassing periods of low, medium and high solar activity, respectively. The latitudinal and longitudinal variation of spread F occurrence was examined by considering different instability triggering mechanisms and precursors which past literature identified as critical to the generation of spread F events. The main findings of this investigation is an inverse solar cycle and annual temporal dependence of the spread F occurrence rate and a different dominant spread F type between low and high European midlatitudes.