Pseudo-dynamical Downscaling of Orographic Precipitation in Future Climate

Any changes in precipitation in the mountains due to climate change will have far reaching consequences, particularly for water resources. However, climate models are run with too course a resolution to capture the processes that control orographic precipitation, and higher-resolution regional climate models remain too computationally expensive to run for long time periods. As a result, many scientists rely on statistical downscaling products that have numerous limitations and instill little faith in their ability to represent changes in orographic precipitation. Here we use a simple weather model that combines linear theory, sophisticated microphysical processes, and with large scale circulation patterns to estimate orographic precipitation. This model was developed to provide a physically realistic, yet computationally tractable model as an intermediate solution between fully dynamic and purely statistical downscaling approaches. The model is applied to a variety of climate models and the results are compared to statistically downscaled precipitation. In addition, we compare output from the model to measured precipitation in current climate, and a short duration high-resolution regional climate model simulation for future climate.