Mean solar quiet daily variations in the earth’s magnetic field along East African longitudes

Solar quiet daily (Sq) variation in the earth’s magnetic field along the East African meridian was studied using data of the H, D and Z components recorded with Magnetic Data Acquisition System of SERC. One year data recorded at ten African geomagnetic observatories was used in the analysis of worldwide solar quiet daily variation (Wsq). The study revealed that the focus of Sq (H) in the southern hemisphere lies at the boundary of low and middle latitude region. Noon-time enhancement of Sq (H) was generally noticed at all stations along the meridian, though it is latitudinal dependent in terms of magnitude as it reduces with distance from dip equator. In addition, night-time variations also occur in small magnitude along African meridian in Sq (H) and Sq (Z) which could be attributed to non-ionospheric sources. Semi-diurnal variation was noticed in Sq (D) at all stations except in AAB that is under the influence of electrojet current. Dusk sector calm condition of Sq (D) current was notice in some stations and the same condition was also noticed at dawn sector in some other stations. The usual sunrise maximum and sunset minimum for D component at stations north of dip equator as well as sunrise minimum and sunset maximum was found to increase with distance away from dip equator. Day-time perturbation of Sq current was noticed to be more pronounced in all the three field elements. Mass plots of annual mean hourly value show contrasting phase pattern about the focus in H element and the results of the variations at each region with the associated standard error. It was concluded from the result of correlation coefficients computed that different currents system flowing in opposite directions could be responsible for contrasting patterns.     

Variability of foE in the equatorial ionosphere with solar activity

This research examined the variability of f_oE in the equatorial ionosphere with solar activity within the equatorial ionospheric anomaly region. Ionosonde data recorded at Ouagadougou (lat. 12.4°N, long. 1.5°W and magnetic dip 1.43°N) were engaged to study the transient variations of the critical frequency of the E-layer (f_oE) and its dependence on solar activity. The study revealed that f_oE increases with the increase in solar intensity of the sun. The variability of the f_oE decreases with increases in the solar activity. The maximum value of the f_oE is at local noon when the ionosphere is stable; the variability at this local time is minimal. The minimum value of the f_oE is at sunrise and sunset, at this period on local time the equatorial ionosphere recorded its maxima variability. Irrespective of the degree of solar activity, f_oE is observed to be maximum in June solstice, followed by the equinoxes and minimum in December solstice. Equinoctial asymmetry occurred in the variation of the relative standard deviation of f_oE with maximum in September/March equinox for low/high solar activity.     

Outreach activities during the 2006 total solar eclipse sponsored by the International Heliophysical Year

The International Heliophysical Year (IHY) is an international program of scientific research to advance our understanding of the physical processes that govern the Sun, Earth and heliosphere. It has a strong educational component, linking research and education. Here, we describe the outreach activities during the 2006 total solar eclipse sponsored by IHY.     

TEC derived from some GPS stations in Nigeria and comparison with the IRI and NeQuick models

Total electron content (TEC) measured simultaneously using Global Positioning System (GPS) ionospheric monitors installed at some locations in Nigeria during the year 2011 (Rz = 55.7) was used to study the diurnal, seasonal, and annual TEC variations. The TEC exhibits daytime maximum, seasonal variation and semiannual variations. Measured TEC were compared with those predicted by the improved versions of the International Reference Ionosphere (IRI) and NeQuick models. The models followed the diurnal and seasonal variation patterns of the observed values of TEC. However, IRI model produced better estimates of TEC than NeQuick at all locations.