Characterization of Sky Conditions Using Clearness Index and Relative Sunshine Duration for Iseyin, Nigeria (Published)
The global solar radiation and sunshine duration data collected over a period of 8 years (2000 – 2007) was examined. The mean monthly clearness index and sunshine duration was calculated and used to develop an Angstrom- page equation for the region. It was observed that the equation has a high correlation coefficient, which gives good results when it was tested with statistical indicators of MBE, MABE and RMSE. Statistical analysis of monthly clearness index showed that the sky conditions at Iseyin were most of time partly cloudy (partly cloudy sky occurred in eight months of the year which is about 66% most of these months falls in the rainy season months). Cloudy sky was only noticed in the month of August which is about 8% and it occurs at the peak of the rainy season. The region has three months of clear sky which is about 25% of the months of the year and they are months in the Harmattan period. The prevailing sunshine condition in Iseyin is predominantly scattered clouds sky except during August and September where a cloudy sky condition is experienced.
Current global climatic trends show a deviation from historic trends and this has necessitated this study. The paper analysed climate change trend and the perceived climatic hazards in Southeast Nigeria. Proportionate sampling technique was used to select a sample of 260 food crop farmers for the study and 232 questionnaires were returned. Secondary time series data on mean annual climate variables for a period of thirty years (1984-2014) were collected from National Root Crop Research Institute Umudike and crop output data from National Bureau of statistics. Data were analysed using descriptive statistical tools like polygon/histograms and line graphs. Also, the extent of damage by climate hazards as perceived by respondents was obtained using likert scale. The rainfall volume variation showed a very unstable pattern with high volatility over years with slightly increasing trend in the study area. Result shows that temperature is significant at 1% level of significance while rainfall volume, rainfall days, relative humidity and sunshine duration were insignificant. Rain day was characterized by unsteady rise and fall trend pattern. The trend also indicated an unsteady change in the movements of the relative humidity and sunshine levels. The result for the occurrence of climate hazards as perceived by farmers show 86.2 %, 64.68%, 63.79%, 77.82% of the respondents perceived to a great extent the impact of flooding, sea level rise, longer period of dry spell and wind storm respectively. Based on the finding, it is concluded that the damaging and devastating effects of climate change is in the increase. It is recommended therefore that adequate adaptive measures and mitigations be put in place to cushion the effect of climate change.