Evaluating the Simulation of CONUS Precipitation by Storm Type in E3SM

Conventional low-resolution (LR) climate models, including the Energy Exascale Earth System Model (E3SMv1), have well-known biases in simulating the frequency, intensity, and timing of precipitation. Approaches to next-generation E3SM, whether the high-resolution (HR) or multiscale modeling framework (MMF) configuration, improve the simulation of the intensity and frequency of precipitation, but regional and seasonal deficiencies still exist. Here we apply a methodology to assess the contribution of tropical cyclones (TCs), extratropical cyclones (ETCs), and mesoscale convective systems (MCSs) to simulated precipitation in E3SMv1-HR and E3SMv1-MMF relative to E3SMv1-LR. Across the United States, E3SMv1-MMF provides the best simulation in terms of precipitation accumulation, frequency and intensity from MCSs and TCs compared to E3SMv1-LR and E3SMv1-HR. All E3SMv1 configurations overestimate precipitation amounts from and the frequency of ETCs over CONUS, with conventional E3SMv1-LR providing the best simulation compared to observations despite limitations in precipitation intensity within these events.

Automated summary

Conventional low-resolution climate models have biases in simulating precipitation frequency, intensity, and timing. High-resolution or multi-scale modeling framework improves the simulation, but deficiencies still exist. Comparing different E3SM configurations, E3SMv1-MMF provides the best simulation in terms of precipitation accumulation, frequency, and intensity from mesoscale convective systems and tropical cyclones. Despite limitations in precipitation intensity, conventional E3SMv1-LR performs the best simulation compared to observations.