Kilometer-Scale Cess-Potter Experiments with SCREAMv1

The Simple Cloud-Resolving Energy Exascale Earth System (E3SM) Atmosphere Model (SCREAM) was created to take full advantage of GPU parallelism and facilitate longer global kilometer-scale experiments with minimal subgrid parameterizations. An outstanding question is whether this type of model will simulate climate feedbacks consistent with 100-km scale climate models. Building on a recent study that found one-year of Cess-Potter type simulations can produce cloud feedbacks similar to those from multi-decade simulations, we will discuss what we have learned from 13-month SCREAM simulations forced with either present-day sea-surface temperatures (SSTs) or with a +4K SST globally uniform perturbation.

The large-scale response generally matches previously reported results with 100-km scale models, suggesting that the lack of a deep convective scheme at the storm-resolving scale does not dramatically alter the response. On the other hand, SCREAM's 3-km configuration shows one of the most positive cloud feedbacks, and hence one of the most positive overall feedbacks, when compared to CMIP6 models. SCREAM simulations run at 12-km resolution also reveal a large resolution sensitivity of the cloud feedbacks. We will discuss the physical underpinnings of the model’s resolution sensitivity and what can be gained from examining climate feedbacks in kilometer-scale modes.