The diurnal cycle of shallow cumulus clouds over land: A single column model study using E3SMv1

Description

In this study, we evaluate the performance of the single column model (SCM) of DOE Energy Exascale Earth System Model Version 1 (E3SMv1) in simulating the diurnal evolution of continental fair-weather shallow cumulus clouds. The case, “Continental Active Surface-forced Shallow cumulus (CASS)”, was developed based on decade-long warm-season observations at DOE ARM US Southern Great Plains (SGP) site and represents a composite behavior of shallow cumulus clouds purely forced by land surface heat fluxes and local atmospheric environment. CASS has been used in our previous large-eddy simulation (LES) studies and is updated to include the most recent observations at SGP overlapping the doppler lidar operation period. The composite forcing data of CASS is updated accordingly as well as the ensemble of shallow cumulus golden days and the associated forcing data for each of the golden days. The performance of E3SMv1-SCM is evaluated with both the composite case and the ensemble of golden days against ARM observations and LES results. E3SMv1-SCM tends to have a weak turbulence mixing and slow boundary layer development. This leads to a late onset of shallow cumulus clouds with a smaller fraction but a larger cloud thickness.