Recent Changes in the Temporal Clustering Patterns of Tropical Rainfall

A variety of recent studies have indicated that the hydroclimates of the tropics and extratropics are changing, resulting in shifts of average seasonal precipitation. While shifts in the mean state are certainly important, there are other more subtle characteristics of rainfall that are of no less practical importance to local water resource management efforts. This study investigates recent changes in the temporal clustering patterns of tropical rainfall using observational multisatellite precipitation data from the Tropical Rainfall Measuring Mission. The Hurst parameter is found to conveniently characterize the intensity of temporal clustering in rainfall data. Substantial changes in clustering intensity are found to occur in many water-stressed regions of the world. Such changes pose a risk to local inhabitants, whose water resource management systems are designed with established rainfall patterns in mind and may not be robust to dramatic changes in the temporal distribution of rainfall within a season.