Ionospheric Minimum Frequency Variability over Ilorin
2026 Volume 17
Bello, S.A.,,bello.sa@unilorin.edu.ng,Department of Physics, Faculty of Physical Sciences, University of Ilorin, Kwara State
Adeniyi, J.O.,,,Department of Physical Sciences, Landmark University, Omu-Aran, Kwara State
Oladipo, M.O,,,Department of Physics with Electronics, Koladaisi University, Ibadan
Shehu J.S.,,,Department of Physics, Bayero University Kano
Sharafa, S.B.,,,Department of Physics, Faculty of Physical Sciences, University of Ilorin, Kwara State
Kazeem, A.K.,,,Department of Physics, Edo State University Iyamho, Edo State.
Akinyemi,G. A.,,,Department of Physical Sciences, Redeemer’s University, P.M.B. 320, Ede, Osun State, Nigeria
Yusuf, K.A.,,Department of Physics, Faculty of Physical Sciences, University of Ilorin, Kwara State
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 (f_min) over Ilorin, Nigeria. We looked at both seasonal and diurnal changes in f_min. 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.
Keyward(s): Ionosphere, ionospheric minimum frequency, f_min, absorption, D-region
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