Diurnal variation of ionospheric profile parameters B0 and B1 for an equatorial station at low solar activity

Abstract

Abstract Parameters B 0 and B 1 are compared with those of the International Reference Ionosphere (IRI), using the Gulyaeva option. The data used are those of Ouagadougou, Burkina Faso, (latitude 12.4°N, longitude 1.5°W, dip 5.9°N) for 1994, a year of low solar activity. Night-time and early daytime B 0 values agree well with those of the IRI. The average value of B 0 for night-time is 73. Major differences occur during the daytime (09:00–18:00 LT) and these are dependent on season. Daytime B 0 shows a diurnal variation which depends on the solar zenith angle χ. The cos(χ) exponents were found to be 0.45, 0.67, 0.56, and 0.75 for winter (January), spring (April), summer (July), and autumn (October), respectively. For B 1 , IRI assumes a constant value of 3 most of the time and this appears to overestimate the experimental B 1 values. The experimental values of B 1 are fairly constant during daytime hours (08:00–15:00 LT), with an average value of 1.7. They are between 2.6 to 3.8 during the evening and night-time period up to 07:00 h.