Intensification of the Daily Wet Day Rainfall Distribution Across Australia

Abstract

AbstractIn Australia and globally, changes in the entire distribution of daily precipitation are poorly understood. An analysis of spatiotemporal changes in the intensity and frequency of wet and all day Australian rainfall between 1958–1985 and 1986–2013 is presented using three different gridded data sets of daily precipitation based on varying underlying station data and interpolation methods. Our analysis method provides a complete picture of changes in the entire distribution as well as a coherent picture of the spatial changes across Australia. We find that the spatial pattern of changes in total rainfall is similar to the pattern of change in wet day frequency but not to change in wet day intensity. Furthermore, more grids across Australia show statistically significant increases than decreases in rainfall intensity throughout the wet day distribution. This means that when it rains (i.e., limited to the wet day distribution), whether it is light, moderate, or extreme rainfall, it rains more.