Title
Using PPE simulations to better understand model physics and parametric sensitivity in EAMv1 over different cloud regimes
Authors
Yun Qian, Vincent E. Larson, Ruby Leung, Wuyin Lin, Ying Liu, Po-Lun Ma, Qi Tang, Hui Wan, Hailong Wang, Heng Xiao, Shaocheng Xie, Guang Zhang, Kai Zhang, Tao Zhang, Shixuan Zhang, and Yuying Zhang
Abstract
The atmospheric component of Energy Exascale Earth System Model (E3SM) version 1 has included many new features in the physics parameterizations compared to its predecessors. Potential complex nonlinear interactions among the physical processes create a significant challenge for understanding the model behaviors and physics, especially at regional scale and process level. To better understand the E3SM atmosphere model behaviors and physics, we conducted a large number of short simulations in which 18 parameters carefully selected from parameterizations of deep convection, shallow convection, and cloud macrophysics and microphysics were perturbed simultaneously using the Latin hyper cube sampling method. Based on those PPE simulations, we identified the different sensitive parameters corresponded to multiple selected interest variables and quantified how the model responds to changes of the parameters over different regions and cloud regimes. We found the cloud forcing has opposite response to some parameters over mid-latitude vs. tropical land. We analyzed how parametric sensitivity changes from stratocumulus to deep convection system over ocean along GPCI cross section. We also investigated how parametric sensitivity evolved with prediction lengthy. The difficulty in simultaneously reducing biases in different regions and cloud regimes highlights the need of characterizing model structural uncertainty (so-called embedded errors) to inform future development efforts.