An Analysis of the Thunderstorm and Disturbance Lines Induced Rainstorm in Ibadan, Nigeria

Abstract

Rainstorms being the single most important physical environmental factor affecting agricultural activities in Nigeria has provoked many climatological studies. Analyses of rainstorms over Nigeria have however largely been confined to the rainstorm characteristics relevant to moisture availability for agricultural purposes in which the indices of seasonality and variability were
mainly employed. The characteristics–the sequence of rainstorm events, duration of rainstorms, rainfall amount, rainfall intensity and the areal coverage of rainstorm events due to thunderstorm and those due to disturbance lines–which determine the exact amount of moisture available, have been relatively neglected. The present study, based on an analysis of 154 rainstorms recorded in Ibadan between 2013 and 2014, is an attempt to examine the effect of these characteristics–duration of rainstorms, rainfall amount and rainfall intensity on areal coverage of rainstorms in Ibadan, Nigeria. Daily rainstorms data, especially the sequence of rainstorm events (percentage), duration of rainstorms (minutes), rainfall amount (millimetre) and the rainfall intensity
(millimeter/hour) were processed for 50 rain gauge stations. The areal coverage of rainstorms (square kilometre) was determined using the square method. Data collected were analysed using multiple regression at p≤0.05. The results indicated a close relationship between a number of rainstorm characteristics. In fact, the correlation coefficient produced between the rainstorms characteristics, showed that a close relationship exist between the duration and rainfall amount, and between the rainfall amount and intensity due to thunderstorm and those due to disturbance lines, which were highly significant (.000 and .000). The results of the analysis showed among other things that the duration of rainstorms, rainfall amount and rainfall intensity were significantly contributed to the areal coverage of rainstorms, though the predictors did not significantly explained the areal coverage of rainstorms in Ibadan.