Investigation of spread F over Nicosia and Moscow during low and high solar activity

Spread F is an ionospheric phenomenon which has been reported and analyzed extensively over equatorial regions. It has also been investigated over midlatitude regions, mostly over the Southern Hemisphere. Over midlatitudes it has, been correlated with geomagnetic activity, travelling ionospheric disturbances (TIDs) and F region uplifts, with Perkins instability proposed as the primary seeding mechanism. The present study deals with the diurnal and seasonal occurrence rate of spread F events observed over two stations at the same longitude namely Nicosia (geographic Lat: 35.29 °N, Long: 33.38 °E) and Moscow (geographic Lat: 55.50 °N, Long: 37.30 °E) during 2009 and 2014 encompassing periods of low, and high solar activity. The main finding of this investigation is the inverse solar cycle and significantly different annual temporal dependence of the spread F occurrence rate over Nicosia and Moscow.