Continental Active Surface-forced Shallow cumulus (CASS) – LES and Single column model tests

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Description

For two decades, June 21, 1997 over ARM’s US Southern Great Plains (SGP) site has served as a benchmark “golden day” for modeling of continental shallow cumulus (ShCu, Brown et al, 2002). Since then, many more observational data have been collected at SGP with more advanced instruments. Based on 13-yr summertime data, a new composite modeling case is built upon 76 golden days which best represent the most typical surface-forced active fairweather shallow cumulus at SGP. This modeling case “Continental Active Surface-forced Shallow cumulus (CASS)” consists both forcing data to drive model and observed cloud statistics to evaluate model. CASS may serve as a new test case for both the cloud-scale large-eddy simulation (LES) studies and the development of convection and cloud parameterizations in large-scale models. CASS data is available to public via http://portal.nersc.gov/project/capt/CASS/ In this study, we use CASS to test the performance of a single column model (SCM) based on DOE newly developed Version 1 of Energy Exascale Earth System Model (E3SM, previously known as ACME). The E3SM-V1-SCM is configured and driven by the exact same forcing as CASS LES runs and is evaluated against both ARM observations and LES results. Through this study we hope to improve understanding of the model physics and its performance on simulating continental shallow cumulus. This work is performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-744055