Regions of the permanent ionosphere instability are identified with 24h daily global W-index maps produced from Global Ionospheric Maps of Total Electron Content, GIM-TEC, provided by Jet Propulsion Laboratory. Planetary Wp index derived from hourly W-index maps from January, 1999, to present, is used to compile Catalogue of more than 270 ionospheric storms which comprise 8% of total database, and the rest represents quiet conditions. The positive storm percentage occurrence (enhanced electron density, pW+) and negative storm occurrence (depleted electron density, pW-) are analyzed in space and time showing dependence on solar activity (SA) and seasons for the global ionosphere and its adopted 240 sub-domains (of latitude bins equal to 10º in the polar regions and 20° elsewhere and 15° hourly longitude bins). A global occurrence of pW+ and pW- during Wp storms follows the 11-year solar cycle with pW- greater than pW+ by about 2 times at high SA and moderate SA while the opposite is observed at solar minimum when pW+ is greater than pW- by about 1.2 times. The regions of enhanced positive storm activity (pW+»10%) are found to occur in the South America, North seashores of Europe and Russia, and between longitudes 30°W to 30°E in Antarctica. Zones of negative storms (pW-»22%) are dominated in Antarctica. The pW+ and pW- depict winter maximum of pW+ and summer maximum of pW- under Wp storm conditions decreasing from high latitudes to minimum at equator throughout all seasons in the both hemispheres. While pW+ and pW- reach 20-25% under the ionosphere storm conditions, the spatial occurrence of pW+ and pW- comprise 6% under quiet conditions at high latitudes which testify on the persistent plasma instability in the ionosphere through more than the total cycle of solar activity.
In this study, the excess heat factor (EHF) index was applied in five (5) selected stations in Nigeria to investigate heat wave characteristics. The EHF originally introduced for use in Australian heatwave monitoring and forecasting, has now been incorporated into a newly designed climpact R-based package used in this work. This work had analysed over 30 years of daily precipitation, minimum and maximum temperature data, as the climate base period, for the selected stations: guinea savannah: Lokoja, Minna; sudan savannah: Kano; sahel: Sokoto, Maiduguri. Daily input data were checked for quality and homogeneity by the climpact software, which also computed and plotted the indices.
Sokoto, Kano, and Minna had the highest heat wave number of six (6), nine (9), and seven (7) respectively in 1987, Maiduguri had highest heat wave number of seven (7) in 1983 while Lokoja had highest heat wave number of five (5) and four (4) in 2005 and 1987 respectively. The lengthiest and shortest heat wave duration (HWD) was identified in 1983 and 1997 respectively for Sokoto, in 1991 and 2005 respectively for Maiduguri, while Kano and Lokoja had the same pattern of heat wave duration over the years. Maiduguri had higher heat wave frequencies than other stations.
Sokoto and Maiduguri had close to severe conditions based on their magnitude levels for both the heat wave amplitude and mean magnitude. Whereas, in Kano there was an almost constant heat wave amplitude and mean magnitude condition over the years. In Minna, opposite conditions as against Maiduguri were identified.
Generally, all results indicated moderate conditions, since severe or even extreme cases rarely occurred. This implied that the southern Sahel and the savannah stations investigated in this study have not been highly affected by heat wave conditions but at some moderate levels over the years under investigation.
The field mapping carried out in the study area was aimed at establishing the local geology of the area, which include the identification of rocks and minerals, and the reconstruction of the petrogenesis and structural evolution of the rocks in the area. Six representative rock samples from twenty two sample locations were selected for thin section petrographic analysis. The results revealed that the area is underlain dominantly by schist with pockets of granite gneiss, quartz-biotite gneiss, quartzite, pegmatite and amphibolite emplaced within the country rock (schist). The schist exhibits alternation of dark and white bands with foliation planes, and trending in the NE-SW direction. The quartz veins are leucocratic, whereas pegmatite contains porphyroblastic texture with the presence of leucocratic minerals (plagioclase). Certain index minerals revealed from the petrographic studies are; quartz, biotite, hornblende, microcline, muscovite, garnet, zircon, sphene, plagioclase and other accessories. These minerals suggested that the area was subjected to Barrovian sequence metamorphism of the amphibolite facies. Structural elements such as joints, fractures, foliations and veins show series of deformational episodes that affected the area, and the major NE-SW trend of the structures suggested Pan African event (600±150 Ma). Aningeje is endowed economically with valuable minerals such as quartz, mica, feldspar and other accessories. The rocks in the area are highly weathered, fractured and jointed. This provides a greater potential for ground water in the area.
An electromagnetic survey was used to delineate conductive and non conductive zones in order to accurately locate electrical resistivity tomography profiles at Ikhueniro refuse dumpsite. The survey comprised four roughly N – S, and E – W direction, very low frequency electromagnetic (VLF-EM) profiles around the perimeter of refuse dumpsite where contaminants/conductive bodies were observed using resistivity imaging and soil analysis method in a previous study. The Fraser and the Karous-Hjelt filters were used in the interpretation of the VLF-EM field data. The data inversion was carried out using a 2-D code which was constrained using previous resistivity survey. The results of the resistivity models calculated from the pseudosections indicate the presences of low resistivity zone up to a depth of 50 m within the subsurface that is in a good agreement with the results obtained from the previous resistivity imaging survey which indicated leachate contamination at the refuse dumpsite.
Fault mapping on Madagali Hills area (Longitudes 13°36’E to 13°41.5’E and Latitude 10°51’N to 10°57.5’N) was done with the objective of producing a structural map of the area and to see the implications of the fault patterns. The area is polygenic, having experienced magmatism, metamorphism and structural deformations. Oldest mapped rocks are gneiss, granite gneiss and schist. These are intruded by Pan African granites. The area has experience both low and high grade metamorphism as proven by the presence of schist and gneisses. Minor intrusive occur as basic and acidic dykes with NE, NW, E-W, and N-S orientations and affect all major rocks. Rock shearing is closely associated with fault zones. Field evidence shows that several drainage channels are fault controlled. Fault intersections are common features. Would the faults serve as good locations for productive bore holes in this semi arid region? Would the intersections serve as avenues for mineralization? These are some issues this paper seeks to address beside the structural data presented.