The Thirty Years Trend Analysis of Harmattan Season Visibility and Temperature in Sahel Zone of Nigeria
Keywords:Harmattan season, Sahel zone, Visibility, Temperature
Climate anomalies have created short-duration climatic oscillations as against the normal cycle and this has posed and is still posing a threat to life and properties in Nigeria. A special climate change unit was created by Nigerian government in 2006 to address this problem. In this study, the meteorological data were obtained from National Oceanic Atmospheric Agency-National Climate Data Centre (NOAA-NCDC) for Sahel zone of Nigeria to analyse the long-term (1988-2017) trend and variability of visibility and temperature. The result reveals that visibility exhibited a decreasing trend while temperature shows an increasing trend over 30-years period. The 30-years seasonal mean visibility is 9.2±2.39, km while the corresponding temperature is 25.12±3.87oC respectively. Decade analysis revealed that the most obvious changes happen during the third decade. Standardize anomaly chart of visibility and temperature also reveal that changes in visibility and temperature are consistent over the study period. A simple regression analysis at p< 0.05 significant level were conducted with visibility as dependent and temperature as independent variables. The results show that the magnitude and nature of the relationship between temperature and visibility depend upon time. However, the trend line is consistently exponential. By dividing the data into ten years interval a much stronger and more significant relationship were obtained.
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