Applied Journal of Physical Science

Ionosonde-f₀F2 measurements and corresponding GNSS TEC measurements have been analysed. Available f₀F2 and TEC data respectively obtained from a pair of ionosonde and GNSS receiver stations of a mid-latitude station, named MO155, located in Moscow (55.8˚N, 37.2˚E), for 2010 and 2014 was used. Data for two years were respectively used in the study to represent years of low and high solar activity. A significant relation between the ionosonde-f₀F2 measurements and the corresponding GNSS-VTEC measurements with correlation coefficients above 0.8 was observed for both periods. The f₀F2/TEC ratios, for the MO155 station illustrated, are typically in the range of about 0.2 to 1.6 Mhz/TECU during the low solar activity period and 0.2 to 2.5 Mhz/TECU during the high solar activity period. The ratio is lower during the day-time, and higher during the nights and early mornings. The analysis of the four seasons for both periods (low solar activity and high solar activity) reveals a strong relationship between TEC and f₀F2 in all the seasons. Significantly, summer season appear to have a different trend from all other seasons with a relatively low correlation. The relationship between TEC and f₀F2 seem to be stronger during period of high solar activity than period of low solar activity. Results from the work indicate that the relationship between f₀F2 and TEC is mostly dependent on the seasons, followed by the level of solar activity, and then the local time. It was shown that the relationship between f₀F2 and TEC is not purely monotonic as suggested earlier; but that this relationship depends on factors like the season, level of solar activity, and local time. Considering the strong relationship between f₀F2 and TEC, the study affirms the method of using TEC as a proxy for f₀F2 estimation.