Abstract
foF2 seasonal asymmetry is investigated at Korhogo station from 1992 to 2002. We show that equinoctial asymmetry is less pronounced and somwhere is absent trough out solar cycle phase. In general, the absence of equinoctial asymmetry may be due to the fact that in equinox and for each solar cycle phase, the asymmetry is due to Russell-McPherron mechanism. The solstice anomaly or annual anomaly is always observed throughout solar cycle phase. The minimum value of ΔfoF2 is inferior than −60% seen during all solar cycle phase at 0700 LT. This annual asymmetry may be due to interplanetary corpuscular radiation.
Highlights
The asymmetry observed in F2 layer critical frequency or in the peak electron density (NmF2) of F2 layer or in the Total Electron Content (TEC) values time variation has been investigated by several authors (e.g. [1]-[7])
The present paper goal is to investigate an asymmetry observed during equinoctial months and that seen during solstice months at Korhogo station (Long 8.427 ̊W; Lat: 9.336 ̊N and dip: −1.88 ̊) by using foF2 value computed in this ionosonde station
The solstice asymmetry called by [3] annual asymmetry or non-seasonal asymmetry is generally explained by the variation of Sun-Earth distance
Summary
The asymmetry observed in F2 layer critical frequency (foF2) or in the peak electron density (NmF2) of F2 layer or in the Total Electron Content (TEC) values time variation has been investigated by several authors (e.g. [1]-[7]). The asymmetry observed in F2 layer critical frequency (foF2) or in the peak electron density (NmF2) of F2 layer or in the Total Electron Content (TEC) values time variation has been investigated by several authors The present paper goal is to investigate an asymmetry observed during equinoctial months and that seen during solstice months at Korhogo station (Long 8.427 ̊W; Lat: 9.336 ̊N and dip: −1.88 ̊) by using foF2 value computed in this ionosonde station. The solstice asymmetry called by [3] annual asymmetry or non-seasonal asymmetry is generally explained by the variation of Sun-Earth distance. This variation can be due to: 1) the variation of O/O2 ratio that modulates the electron loss coefficient in the F2-layer [13]. The paper plan is as follows: after materials and methods, we present our results and end the paper by discussion and conclusion
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