Year to year variation of rainfall rate and rainfall regime in Ota, southwest Nigeria for the year 2012 to 2015

摘要

The tropics is characterized to have convective type of rainfall which has highudoccurrence of rainfall compared to the temperate regions of the world. In this paper, theudaccumulation of rainfall in Ota, Southwest, Nigeria (6o 42 N, 3o 14 E) has been analysed toudpresent the one-minute rainfall rate and the predominant type of rainfall. Four years’ data usedudfor this study was taken using the Davis Wireless vantage Pro2 weather station at CovenantudUniversity, Ota, Ogun State. The data collected were used to analyse the one-minute rainfalludrate and different types of rainfall predominant in this region. For the prediction andudmodelling of rain attenuation at microwave frequencies for a region like the Nigeria at variousudpercentage of time, one-minute rainfall rate is required. Nigeria falls into the P zone of 114udmm/hr. as per International Telecommunication Union – Recommendation (ITU-R). Theudanalysis carried out indicated that the measured yearly averaged maximum one-minute rainfalludrate for 2012, 2013, 2014 and 2015 are 157.7 mm/h, 148.0 mm/h, 241.2 mm/h and 157.3udmm/h respectively. It also indicated that the drizzle type of rainfall is predominant in contrastudto established fact that thunderstorm occurs more in the tropics.