Scale Issues in the Development of Future Precipitation Scenarios



Many of the processes that govern precipitation occurrence and intensity occur at spatial and temporal scales that remain unresolved by the current generation of climate models. The resulting mismatch between the information reliably provided by such models and the needs of researchers assessing impacts associated with changes in precipitation has led to the development of downscaling techniques. In this paper, the need for downscaling is demonstrated by describing (1) the difference between real-world precipitation-governing processes and their representation in climate models and (2) the differences between theoretical expectations of precipitation changes at large and small scales in a warmer world. With a primary focus on empirical-statistical downscaling, the general strategy for developing regional scenarios is described along with outstanding issues that are likely to shape the next decade of downscaling research.