F-region variability over the anomaly crest region

Abstract

Day-to-day variability in the critical frequency of F-layer (f_oF₂) over Ahmedabad has been examined. The hourly data for the months of January, March and July for the high sunspot year 1969 and low sunspot year 1996 have been analysed to study the variability. Daily variations on different days of the month, standard deviations and the normalized deviations at each hour have been studied. The normalized standard deviations are up to ±30% during night hours and up to ±15% during day hours. While the variability during day hours is mainly because of the variability in the electric field (electrojet strength) that gives rise to vertical drift and subsequent ionization anomaly, the variability during night hours is also contributed by the variability in thermospheric neutral winds and temperature.