Rate of total electron content index (ROTI) characteristics over Cyprus

To explore the characteristics of nighttime ionospheric irregularities over Nicosia (Cyprus), all ionograms recorded by the DPS-4D digisonde during 2016 have been analyzed. A subsequent detailed investigation was performed to identify the possible dominant triggering spread F mechanisms within the framework of Perkins instability. To understand the occurrence and intensity of ionospheric L-band irregularities over Nicosia the Rate of Total Electron Content (TEC) Index (ROTI) and detrended TEC maps have been analysed in association with spread F activity. The present study demonstrates that the majority of range spread F (RSF) cases identified for all notable ROTI (>0.15TECU/min) activity in summer which also coincides with MSTID activity over Nicosia, suggesting induced gravity waves or polarization electric fields as the driving mechanism for nighttime ionospheric irregularities over Nicosia. Diurnal and seasonal features are also presented. Maximum irregularity occurrence was observed from 18:00 to 05:00 UT with a seasonal maximum occurrence in July-August.