Climate Variability Impact on the Frequency of Occurrence of Mesoscale Convective Systems in Northern Nigeria

Abstract

Mesoscale Convective Systems (MCSs) form an important component of meteorology in West Africa, and in particular, contribute substantially to precipitation totals. Several authors focused majorly on the contribution of these systems to precipitation and the damages that accompanied it. But in the event of current climate change, it is expected that storm occurrences especially over the tropics will also be impacted due to variability or changing in climate especially in Northern Nigeria which has experienced some extreme weather events over the years. The study was carried out in eight (8) different states within the savannah region of Nigeria. Monthly total rainfall, mean monthly temperature, relative humidity and daily Mesoscale Convective Systems (MCSs) (thunderstorms and line squalls) data of 31 years was used. Man-Kendall and Coefficient of variation (CV) method were used to analyze the data. There were various degrees of variations in some of the data analyzed based on the location of the station. The frequency of occurrence of these systems showed that its number (peals) decreases with an increasing latitude for stations north of 10°N with the north-eastern part of the country recording a decrease of almost one-third between 1981 and 2010. Hence, monsoon type of precipitation can be seen to be contributing more to the total annual rainfall in the northern part of Nigeria in contrast to earlier studies which gave Mesoscale Convective Systems (MCSs) 95% contribution rate.