Effects of Variations in Sea and Land Surface Temperature on Rainfall Pattern over Nigerian Coastal Zone

This study evaluated the variations in sea and land temperature from 1901 to 2013 with a view to examining their effects on rainfall pattern in the coastal zone of Nigeria. It used the National Oceanic and Atmospheric Administration (NOAA) monthly mean sea surface temperature (SST) over the Atlantic Ocean (longitude 0o E - 8o.20′ E and latitude 1oN - 3o.50′ N). Land Surface Temperature (LST) and rainfall dataset sourced from the archive of the University of Delaware (UDEL) and ground station observations (NIMET) over four selected coastal locations (Calabar, Lagos, Port-Harcourt and Warri) were also used. The mean observations of rainfall and temperature of NIMET and UDEL for the overlapping period (i.e. 1974-2013) were compared Using paired T-test and Percent Bias. The annual and seasonal trends in these climatic variables were examined using their deviations from means and trend analyses. The study then employed Pearson multiple linear regression analysis to evaluate the combined effects of LST and SST on rainfall pattern over the study areas. The results revealed the highest values of SST and LST in MAM and the lowest in JJA season.  It rained in all months across the stations with the maximum rainfall (163.5 - 471.2 mm/month) in JJA and the least (24.0 - 47.2mm/month) in DJF. The comparison of both UDEL and NIMET observations suggested no significant difference between both datasets at P = .05.  The results demonstrated increasing trends in both SST (0.012oC year-1) and LST (0.003 to 0.007oC year-1). Both SST and LST significantly influenced rainfall pattern (0.445 ≥ R ≤ 0.731; R > 39%) at P = .05. The contributions of SST to rainfall variations were, however, significantly higher (0.530: 0.422) than those of LST (0.452: 0.215) in Lagos and Port-Harcourt due to the proximity and locations of these stations to the Atlantic Ocean. Keywords: Sea and land surface temperature, rainfall variations, effects, coastal zon

The effect of climate change on solar radiation in Nigeria

In this study, global solar radiation over Nigeria was simulated under an enhanced atmospheric CO2 level using the International Centre for Theoretical Physics (ICTP) Regional Climate Model version 3 (RegCM3) for the period 1981 to 2100 with ECHAM5 GCM as the lateral boundary conditions. The simulated seasonal global solar radiation bias for the RegCM3 with NIMET and NASA observed datasets in the control period are of similar magnitudes and showed a mixture of persistent positive and negative biases ranging between �10% and 30%. The model generally underestimates solar radiation (biases �10% to �30%) across the whole country in most of the months. In addition, it overestimates radiation (biases +2–30%) over the northern region of the country. Alongside the present climate (1981–2010), three future periods were considered viz: period 1 (2011–2040), period 2 (2041–2070) and period 3 (2071–2100) for the potential future changes. The seasonal potential future changes in period 1 (i.e. potential future changes with respect to 2040) showed a reduction in the range of 0% (North) to 3.27% (South) whereas more reduction in global solar radiation is observed in period 2 (i.e. 2041–2070 minus present climate) having general decrease ranging from 0.11% to 3.39% with the least value in April (Middle-belt) and the largest in the South zone (March). Potential future changes in period 3 (i.e. 2071–2100 minus present climate) is generally characterized with mixed increase and decrease in global solar radiation across the country than the previous two periods (1 and 2). For the annual potential future changes, RegCM3 model predicted a decrease in solar radiation towards the end of the century with more reduction found in the South zone and the least in the North region. Furthermore, future changes in global solar radiation across the zones in all the periods are however found to be insignificant at p 6 0.01