Assessment of Precipitating Marine Stratocumulus in EAMv1: A Case Study during the ARM MAGIC Campaign

Description

The ARM observations, particularly the drizzle retrievals, during the MAGIC field campaign provide a comprehensive observational reference to evaluate the marine stratocumulus precipitation processes in E3SM model. Furthermore, LES simulations add extra information to the process-level evolution using single-column mode simulations with the same large-scale forcing as the LES simulations. This study aims to use ARM observation and LES simulation to estimate: 1) the model performance on simulating precipitating MBL clouds, and 2) the precipitation processes in EAMv1 SCM simulations. Our results show that the single-column mode simulation generally captures the time evolution of the marine stratocumulus cloud layer and the BL structure. The main biases include too late Sc to Cu transition, too much precipitation and too moist low-level BL. In terms of the precipitation processes, EAMv1 produces a reasonable cloud-base rain rate for a given LWP. EAMv1, however, produces unrealistic double-peak precipitation profiles and has a too low evaporating zone. We will propose several model changes to improve the representation of the precipitation processes without degrading the model performance on the other aspects. Acknowledgement: This work is supported by the ASR Program for the Office of Science of the U.S. DOE. This work was performed under the auspices of the U.S. DOE by LLNL under contract DE-AC52-07NA27344. LLNL-ABS-768118