Variation of foF2 during low and high solar activity over Thailand equatorial latitude station

This paper presents the variation of the F2 layer critical frequency (foF2) in different phases of the 24th solar cycle at Thailand equatorial latitude station, namely Chumphon (10.72°N, 99.37°E and magnetic dip 3.3°N). Monthly median of foF2 values every 15 minutes in March, June, September and December are manually scaled from the FM-CW ionosonde of the year 2009 and 2014 for investigating the diurnal and seasonal variation during low and high solar activity. The observed foF2 results show a similar feature in diurnal and seasonal variations with higher during daytime, lower during nighttime. The maximum values occur during equinox (March and September) seasons while the minimum levels occur in solstice (June and December) seasons. The advantages of this study are much important for understanding, managing and designating the HF communication systems. Furthermore, it can be used to improve the ionospheric model and map at the magnetic equator.