Variation of bottomside profile parameters B0 and B1 at high solar activity for an equatorial station

Abstract

Abstract Diurnal and seasonal variations in experimental profile parameters B0 and B1 are examined, at high solar activity, for Ouagadougou, Burkina Faso, an equatorial station in Africa (latitude 12.4°N, longitude 1.5°W, dip 5.9°N). The diurnal variations for B0 indicate a solar zenith angle dependence that can be described as B0 = A cosn (χ) with n = 0.40, 0.51, 0.46, and 0.71 for Winter, Spring, Summer and Autumn, respectively. The seasonal effect is most pronounced from 10:00–18:00 LT. Within this period, B0 is highest in Spring and lowest in Winter. A comparison of experimental B0 with the IRI B0 shows that the greatest discrepancy occur from about 11:00 to about 18:00 LT. Both are closer during most of the night time hours and in the early hours of the daytime. There is no obvious solar zenith angle dependence in B1. The range of variation for all seasons, during the day time (10:00–18:00 LT) is 0.8. For the remaining part of the 24 h period, the range is about 1.8. Generally, there is an overestimation of B1 by the IRI model.