Combining regional mesh refinement with vertically enhanced physics to target marine stratocumulus biases as demonstrated in the Energy Exascale Earth System Model version 1

In this paper we develop a novel framework aimed to significantly reduce biases related to marine stratocumulus clouds in general circulation models (GCMs) while circumventing excessive computational cost requirements. Our strategy is to increase the horizontal resolution using a regionally refined mesh (RRM) over our region of interest in addition to using the Framework for Improvement by Vertical Enhancement (FIVE) to increase the vertical resolution only for specific physical processes that are important for stratocumulus. We apply the RRM off the coast of Peru in the southeastern Pacific, a region that climatologically contains the most marine stratocumulus in the subtropics. We find that our new modeling framework is able to replicate the results of our high-resolution benchmark simulation with much fidelity, while reducing the computational cost by several orders of magnitude. In addition, this framework is able to greatly reduce the long-standing biases associated with marine stratocumulus in GCMs when compared to the standard-resolution control simulation.

Automated summary

In this study, a novel framework is developed to reduce biases in general circulation models (GCMs) related to marine stratocumulus clouds, while minimizing computational costs. The framework utilizes a regionally refined mesh (RRM) to increase horizontal resolution, and the Framework for Improvement by Vertical Enhancement (FIVE) to enhance vertical resolution for specific physical processes important for stratocumulus. The framework is successfully applied off the coast of Peru in the southeastern Pacific, effectively replicating high-resolution benchmark simulation results with reduced computational cost and improved accuracy compared to standard-resolution simulations.