ON THE RELATIONS OF THE RAINFALL VARIABILITY AND DISTRIBUTION WITH THE MEAN RAINFALL OVER INDIA

Along with averages, rainfall variability and distribution are important climatological information. In this study, using 114 years (1871-1984) data of 306 stations, it is demonstrated that the variability and spatial distribution of annual, summer monsoon and monthly rainfall are highly dependent upon the respective period mean rainfall variation over India. The magnitude of three selected absolute measures of variability, e.g. standard deviation, absolute mean deviation and mean absolute interannual variability is found to increase linearly with mean rainfall. In order to describe the relation between the rainfall frequency distribution and the mean rainfall, a linear regression between the rainfall amount expected with a specified exceedance/non-exceedance probability and the mean rainfall amount is presented. Highly significant linear curves for a large number of probabilities specified in an average probability diagram clearly demonstrate the dependence of the rainfall frequency distribution on mean rainfall over India.