A MODIFIED WEATHER GENERATOR (WGEN) FOR THE GENERATION OF DAILY WEATHER VARIABLES

Long series of daily weather data are frequently needed to evaluate diachronic climatic impact on water resources,the effects of watershed changes on hydrology and to use in a variety of weather and general circulation models.A computer generation model called WGEN that was developed in the United States of America,was modified in this study and applied to Nigerian weather data spanning the period between 1969 to 1988 and covering 17 sites located in the different climatic zones in Nigeria.The model generated the monthly mean maximum and minimum temperatures,solar radiation,total rainfall,and number of wet and dry days with high accuracy,95% of the times.The Mann-Whitney U-test revealed that the number of months per year for which observed and generated weather variables were significant,was less than 4 in majority of the sites.