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IONOSPHERIC MINIMUM FREQUENCY VARIABILITY OVER ILORIN

📅 2026 📚 Volume 17

Authors

• Bello, S.A.,,,
• Adeniyi, J.O.,,,
• Oladipo, M.O,,,
• Shehu J.S.,,,
• Sharafa, S.B.,,,
• Kazeem, A.K.,,,
• Akinyemi,G. A.,,,
• Yusuf, K.A.,,
•

Abstract

Using ground-based Digisonde records from the University of Ilorin Ionospheric Observatory (8.5° N, 4.5° E) over the year 2010, this study examined the equatorial ionospheric minimum frequency ( ) over Ilorin, Nigeria. We looked at both seasonal and diurnal changes in . From a pre-dawn minimum to an afternoon maximum, the diurnal pattern shows a consistent increase, which is followed by a fall after sunset. Seasonal findings reveal significant daytime variability between 1200 and 1400 UT (LT = UT + 1 h), with the highest noon peak observed during the equinoxes and the lowest during the solstices. Midday peak values ranged between 2.05 and 2.7 MHz across the months studied. The increased electron density in the ionospheric D-layer is responsible for these observed peaks.

Keywords

Ionosphere ionospheric minimum frequency absorption D-region.