Dependence of the Daily NmF2 Values over Mid-Latitude Stations on the Solar and Geomagnetic Activity

Abstract

The results of studies of the dependence of the daily electron concentration at maximum of the F2 ionospheric layer in January 2008–2015 on the solar and geomagnetic activity are presented. The solar radio emission flux density indices F_10.7 and geomagnetic activity indices A_p were averaged over 27 days, and 〈F_10.7〉₂₇ and 〈A_p〉₂₇, respectively, were obtained. Based on the data of three stations, 27-day median (with the middle of January 15) daily N_mF2 variations were obtained for 2008–2015. Based on these data, the following paradox was discovered: in January 2014, when the values of the solar activity index F_10.7 were larger than in 2015, the dailyN_mF2 values were smaller. Averaging over four hours of local daytime (10:00–14:00 LT) gave the daily average January 〈N_mF2〉 values for each selected station for each year. To solve this paradox, a double linear regression of 〈N_mF2〉 on 〈F_10.7〉₂₇ and 〈A_p〉₂₇ was constructed. Due to this, it was concluded that the contribution of geomagnetic activity to daily January 〈N_mF2〉 values is positive. A comparison of the mean square errors of the linear and double linear regressions for 〈F_10.7〉₂₇ and 〈F_10.7〉₈₁ showed that the use of 〈F_10.7〉₂₇ led to smaller errors than the use of 〈F_10.7〉₈₁.