Comparing two weather generator‐based downscaling tools for simulating storm intensification and its impacts on soil erosion under climate change

Abstract

AbstractStorm intensification is projected to increase under climate change; however, it is quite challenging to statistically downscale storm intensification for climatic impact assessment. The objectives of this study are to compare two weather generator‐based tools in simulating daily precipitation extremes at a point scale, both with and without storm intensification options, and to further evaluate the responses of simulated surface runoff and soil loss to generated precipitation extremes under various cropping and tillage systems at a station in central Oklahoma, U.S.A. Results show that all data sources including raw GCM, raw RCM, and statistically downscaled GCM datasets are capable of providing information on future storm intensification, depending on particular ensemble members or models in each source. Thus, it is recommended that all data sources including as many members as possible should be used in model screening. Compared with the SYNthetic weather generaTOR (SYNTOR), the Generator for Point Climate Change (GPCC) tool tends to generate a stronger storm intensification, partially because GPCC takes into consideration the increased variance of monthly precipitation as projected by GCMs in adjusting daily precipitation variance for future climate generation. However, there are no discernable differences between storm intensification options with each tool because weaker signals of storm intensification are projected for the study site coupled with a projected decline in future annual precipitation. Simulated soil loss and surface runoff rates with GPCC were significantly greater than those with SYNTOR due to GPCC generating more frequent and heavier storms. Given the sizable differences in extreme precipitation generation, both tools could be used to generate a range of the potential impacts of storm intensification under climate change on soil erosion and surface hydrology.