Cloud feedback is the main source of uncertainty in future global warming simulated by global climate models, primarily because the response of clouds involves sub-grid processes that are parameterized and may not be accurately represented in models. This motivates us to examine high resolution models that explicitly resolve deep convective motions across the globe to determine how and why cloud feedbacks may differ from their coarse climate model counterparts. In this study, we analyze mean-state cloud properties and cloud feedback components in the DOE’s global storm resolving model, the Simple Cloud-Resolving E3SM Atmosphere Model (SCREAM), through a pair of one-year atmosphere-only simulations prescribed with observed sea surface temperature and with a perturbation of uniform 4K warming. These simulations include ISCCP simulator diagnostics, allowing for a more rigorous comparison between observed and modeled cloud fields as well as a more detailed examination of cloud feedbacks. Two horizontal resolutions of SCREAM (3 and 12 km) are examined, and both simulations depict a realistic spatial structure of mean-state cloud cover but with smaller magnitude compared with satellite observations. SCREAM simulates a strong positive high-cloud altitude feedback and positive optical depth feedbacks over high-cloud and marine stratocumulus cloud regimes. It also simulates a surprisingly negative low-cloud amount feedback over broad swaths of the tropical oceans, while the high-latitude low cloud optical depth feedback and tropical anvil cloud feedback are neutral. Summing the contributions from all cloud types yields a positive total cloud feedback that lies within the range of CMIP5 and CMIP6 models for both simulations, with 3-km model falling at the higher end of the distribution.

[This work was performed under the auspices of the DOE by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-861432]