Abstract

This study investigates the possible effects of solar and geomagnetic activity on climatic parameters in Nigeria. Data of sunspot number and geomagnetic aa index from 1950 – 2012 and 1950 – 2010 were used as solar indices respectively. Monthly mean daily rainfall, minimum and maximum temperature data from 1950 – 2012 for 15 stations were used as climatic parameters. Descriptive and bivariate analyses as well as Mann-Kendall trend test were employed in analyzing the data, while power spectral density (PSD) analysis was performed using XLSTAT. The results reveal significant upward trends in the variability of minimum and maximum temperature, whereas no significant trends were observed in the variation trend of rainfall for the period under study. This was ascertained from the Mann-Kendall trend test. The variability in rainfall and temperature could be evidence of climate change. The correlation between solar indices and climatic parameters were statistically insignificant at 0.05 level of significant. Similar periodicities were observed in the spectrum of solar and geomagnetic activity indices, as well as the climatic parameters. There were indications of Schwabe, Hale and Gleissberg cycles on rainfall and temperature spectral. These depict signatures of solar and geomagnetic activities. Hence, we infer that, apart from human activities, solar and geomagnetic activities could play important roles in climate change observed in Nigeria.

Key words: Solar activity, periodicities, climate change, Nigeria.