Evaluating the EPA Dynamically Downscaled Ensemble (EDDE) for Hydrological Endpoints

Since 2009, the U.S. Environmental Protection Agency (EPA) has produced dynamically downscaled simulations over a North American domain. These datasets are collectively known as the EPA Dynamically Downscaled Ensemble (EDDE). The initial dataset (EDDEv1) includes downscaled output of global climate models (GCMs) from Phase 5 of the Coupled Model Intercomparison Project (CMIP5). We uploaded hourly output from selected atmospheric and land variables in EDDEv1 for free download via Amazon Web Services (AWS) in July 2024. This includes output that depicts a 31-year historical period and a 76-year future period.

Simulations driven by CMIP6 GCMs are underway for version 2 of EDDE. We plan to publicly release EDDEv2 output via AWS throughout 2025. This talk includes a summary of EDDEv2 development choices, the evolution from EDDEv1 to EDDEv2, and an assessment of value added to a continuously integrated historical simulation that comprises 30 years. In our first historical experiment in EDDEv2, the ~100 km resolution version of the Max Planck Institute Earth System Model (MPI-ESM1.2-HR) provides forcing for the configuration of the Weather Research and Forecasting (WRF) model that we use for dynamical downscaling over a domain with 12-km horizontal grid spacing.

Here, we describe performance of selected EDDEv2 fields relative to the driving GCM and to other available downscaling products for novel hydrological applications that EDDE may inform. These include applications affected by the North American monsoon, cryosphere variability, and changes to the Great Lakes. EDDE is also uniquely suited for applications that require high temporal resolution output, such as sub-daily and sub-hourly temperature, humidity, and precipitation. Finally, this presentation serves as a solicitation for feedback on additional user needs and variables of interest to the hydrological modeling community.