Project Scientist National Center for Atmospheric Research Boulder, Colorado
The US Bureau of Reclamation (Reclamation) and the National Center for Atmospheric Research (NCAR) are working towards more rigorous inclusion of climate change information into Reclamation’s periodic comprehensive review (CR) procedures. Currently there are very limited pathways or capabilities for climate change information to be incorporated into the comprehensive review process. Specifically, we are developing information for incorporating climate change into the hydrological hazards component of the CR using model output from the 6th Coupled Model Intercomparison (CMIP6) (coordinated by the Intergovernmental Panel on Climate Change) and other recent Earth System Model (ESM) and downscaling capabilities that may better quantify uncertainty and provide larger samples of potential future storms. Large ensembles of multiple ESMs are now available that can more robustly quantify internal variability of the climate system as well as some of the ESM model uncertainty. Further recent statistical downscaling technique development, hydrological model development, and continued computational resource increases enable dynamic and statistical downscaling of these large ensembles of climate models and perform large-domain hydrological modeling.
Two primary efforts are underway, 1) developing change estimates of many large precipitation events across specific basins from historical to future periods using dynamic downscaling and; 2) developing western US-wide hydrologic model output for ESM large ensembles (ESM-LE) to quantify internal variability and emergence of any climate change signals in precipitation and flow volumes. We will present results of dynamic downscaling across the Lahontan Valley (NV) and Taylor Park (CO) watersheds as well as initial precipitation and hydrological modeling of our western US-wide ESM-LE workflow. The analysis will focus on changes across events, accumulation time intervals (e.g., 3, 5, 7 days), and the concept of time of emergence of the change signal above the noise of internal variability across multiple CMIP6 ESMs.
