Disaggregation of Daily Rainfall

Abstract

This study represents an attempt to model the disaggregation of daily rainfall at a point into individual storms for the summer rainy season in southeast Arizona. The purpose of the model is to simulate the number of storms per day and the amount, duration and time of occurrence of each event while maintaining daily statistics. Various storm ratios are introduced to describe the disaggregation of a daily amount into individual storm amounts. Marginal distributions are fit to the storm ratios and event starting times. On multiple-event days, starting times are obtained through the use of order statistics. Conditional distributions are fit to the number of storms per day, given a daily amount, and the duration of each event, given a storm amount. The simulated data compare favorably with the observed data. Statistical tests indicate that the model adequately transforms daily rainfall into a sequence of individual storms.