Submitted to: Annual Hydrology Days Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: August 17, 1999
Publication Date: N/A
Technical Abstract: Identification of storms in a record of precipitation is commonly needed for analyses of precipitation data. A method often used for determining the minimum dry time that identifies storms, called the "critical duration" (CD), is the "exponential method". The CD is found through an iterative procedure in this method by determining the dry-period duration at which the frequency distribution of times between storms is exponential. In a previous study CD was mapped seasonally over the plains area of eastern Colorado, southeastern Wyoming, southwestern Nebraska, and eastern Kansas. In this study, the seasonal and spatial variability of the frequency distributions of times between storms resulting from the earlier determination of CD is investigated over the same 4-state area. Frequency distributions of times between storms are useful for stochastic simulation of the occurrence of storms. Consequently, the spatial variability of these distributions is important to parameterize such a model. This investigation explores the spatial and seasonal variability of these distributions. In particular, the mapping of the one parameter of the exponential distribution (mean and standard deviation are equal) is investigated. The spatial and seasonal variability of these distributions has additional utility for determining the severity (probability of occurrence) of rainless periods for drought studies and monitoring, they can be used as a surrogate variable for crop stress, and they can be coupled with soil moisture models to determine the frequency of occurrence of soil moisture deficits.