Understanding Cloud and Convective Characteristics in Version 1 of the E3SM Atmosphere Model

By S. Xie, Wuyin Lin, Philip J. Rasch, P. Ma, Richard B. Neale, V. Larson, Y. Qian, P. Bogenschutz, Peter M. Caldwell, P. Cameron-smith and 8 more. Journal of Advances in Modeling Earth Systems, 2018

153 citations recorded by the source corpus.

This study provides comprehensive insight into the notable differences in clouds and precipitation simulated by the Energy Exascale Earth System Model Atmosphere Model version 0 and version 1 (EAMv1). Several sensitivity experiments are conducted to isolate the impact of changes in model physics, resolution, and parameter choices on these differences. The overall improvement in EAMv1 clouds and precipitation is primarily attributed to the introduction of a simplified third‐order turbulence parameterization Cloud Layers Unified By Binormals (along with the companion changes) for a unified treatment of boundary layer turbulence, shallow convection, and cloud macrophysics, though it also leads to a reduction in subtropical coastal stratocumulus clouds. This lack of stratocumulus clouds is considerably improved by increasing vertical resolution from 30 to 72 layers, but the gain is unfortunately subsequently offset by other retuning to reach the top‐of‐atmosphere energy balance. Increasing vertical resolution also results in a considerable underestimation of high clouds over the tropical warm pool, primarily due to the selection for numerical stability of a higher air parcel launch level in the deep convection scheme. Increasing horizontal resolution from 1° to 0.25° without retuning leads to considerable degradation in cloud and precipitation fields, with much weaker tropical and subtropical short‐ and longwave cloud radiative forcing and much stronger precipitation in the intertropical convergence zone, indicating poor scale awareness of the cloud parameterizations. To avoid this degradation, significantly different parameter settings for the low‐resolution (1°) and high‐resolution (0.25°) were required to achieve optimal performance in EAMv1.

Subfields: Atmospheric Science, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/efd9393b7baf6b23eecdf88f184eac572a67facc

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Atmospheric Science

1. J. Golaz
2. Guang J. Zhang
3. V. Larson
4. Richard B. Neale
5. Wuyin Lin
6. S. Xie
7. J. Richter
8. Xiaohong Liu

In Global and Planetary Change

1. J. Golaz
2. Guang J. Zhang
3. V. Larson
4. Richard B. Neale
5. S. Xie
6. Wuyin Lin
7. J. Richter
8. Philip J. Rasch

Citations in the corpus

• An Overview of the Atmospheric Component of the Energy Exascale Earth System Model (2019, methodology): “CAM5 tropical CRE biases appear centered on regions of deep convection, while EAM low‐latitude biases are located primarily in regions of trade cumuli and summertime stratocumulus (Xie et al., 2018).”
• The DOE E3SM Coupled Model Version 1: Description and Results at High Resolution (2019, methodology): “The impact of increased vertical resolution on E3SM is discussed in Rasch et al. (2019) and Xie et al. (2018).”
• The DOE E3SM Coupled Model Version 1: Overview and Evaluation at Standard Resolution (2019, unknown): “The underpredicted coastal stratocumulus is due to both the use of CLUBB and model retuning (Xie et al., 2018).”
• Improved Diurnal Cycle of Precipitation in E3SM With a Revised Convective Triggering Function (2019, methodology): “Based on these earlier studies, this study proposes a new convective triggering function by combining the dCAPE trigger developed in Xie and Zhang (2000) and the Unrestricted air parcel Launch Level (ULL) trigger described inWang et al. (2015) to improve convection initiation in climate models.”