COUPLING EFFECT OF SOLAR WIND AND MAGNETOSPHERE ON THE IONOSPHERE AND ITS EFFECTS ON RADIO SIGNALS

Abstract

The effect of the interaction between the solar wind and magnetosphere on the ionosphere provide even a greater challenge as it introduces more irregularity in the behavior of the ionosphere, which has already possess a challenge to scientists and users. The climatology of the coupling effect of solar wind and magnetosphere on the ionosphere and its effects on radio signals were investigated using ionosonde data from an equatorial anomaly station of the African sector, Ouagadougou, Burkina Faso (lat. 12.4o N; long. 1.5o W; dip lat. +1.45). Geomagnetic and solar wind data were also obtained from Space Physics Interactive Data Resource (SPIDR) and OMNI websites. The data covered a period of 22 years (1976-1997) which fall within solar cycles 21 and 22. The ionospheric parameters used were the peak electron densities; 2 NmF , 1 NmF , NmE and their heights; 2 hmF , 1 hmF and ' hE. Geomagnetic and solar wind indices were; disturbance storm time ( Dst ), interplanetary magnetic field ( IMF ), southward component of interplanetary magnetic field ( Bz ), solar wind speed (Vsw ) and solar wind dynamic pressure ( Psw ). The diurnal, seasonal and solar cycle variations of the ionospheric data were analyzed and hourly, daily, and annual variations of geomagnetic and solar wind data were equally examined. The correlation and regression analysis were carried out between ionospheric parameters, geomagnetic and solar wind indices. The results indicate that all the ionospheric parameters show obvious diurnal variation and solar cycle effect except h 'E which does not show solar cycle effect. NmF2 seasonal variation exhibits semi-annual and winter anomalies. NmF2 is maximum in March/September equinox and minimum in June solstice at all levels of solar activities. NmE is maximum mostly at equinoxes and minimum mostly in December solstice at all levels of solar activities. It was also observed that hmF2 is maximum mostly in March equinox and minimum mostly in December solstice during the period of high and moderate solar activities and it was maximum mostly in June solstice and minimum mostly in December solstice during the years of low solar activity. The long term variation of geomagnetic activity and solar wind indices show that only IMF exhibits 11 years solar cycle variation while vii other indices did not show solar cycle variation. It was observed that IMF and Dst indices have major effects on the peak electron density of 2 F and 1 F layers; 2 NmF , 1 NmF and their heights; 2 hmF and 1 hmF while IMF and Psw indices have major effects on the peak electron density of E layer ( NmE ). Bz and Psw indices have major effects on the virtual height of E layer ( ' hE). Hence, IMF and Dst indices have major effects on the equatorial ionosphere over Ouagadougou, an equatorial anomaly region. Overall results will assist relevant users and designers of Earth-space radio communication systems in the region.