Parametric behaviors of CLUBB in simulations of low clouds in the C ommunity A tmosphere M odel ( CAM )
- Pacific Northwest National Laboratory, Richland Washington USA, State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences Beijing China, Climate Change Research Center, Chinese Academy of Sciences Beijing China, Institute for Climate and Global Change Research, School of Atmospheric Sciences, Nanjing University Nanjing China, Collaborative Innovation Center of Climate Change Jiangsu Province China
- Pacific Northwest National Laboratory, Richland Washington USA, Institute for Climate and Global Change Research, School of Atmospheric Sciences, Nanjing University Nanjing China, Collaborative Innovation Center of Climate Change Jiangsu Province China
- Pacific Northwest National Laboratory, Richland Washington USA
- University of Wisconsin‐Milwaukee, Milwaukee Wisconsin USA
- National Center for Atmospheric Research Boulder Colorado USA
- State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences Beijing China
In this study, we investigate the sensitivity of simulated low clouds to 14 selected tunable parameters of Cloud Layers Unified By Binormals (CLUBB), a higher order closure (HOC) scheme, and 4 parameters of the Zhang-McFarlane (ZM) deep convection scheme in the Community Atmosphere Model version 5 (CAM5). A quasi-Monte Carlo (QMC) sampling approach is adopted to effectively explore the high-dimensional parameter space and a generalized linear model is applied to study the responses of simulated cloud fields to tunable parameters. Our results show that the variance in simulated low-cloud properties (cloud fraction and liquid water path) can be explained by the selected tunable parameters in two different ways: macrophysics itself and its interaction with microphysics. First, the parameters related to dynamic and thermodynamic turbulent structure and double Gaussians closure are found to be the most influential parameters for simulating low clouds. The spatial distributions of the parameter contributions show clear cloud-regime dependence. Second, because of the coupling between cloud macrophysics and cloud microphysics, the coefficient of the dissipation term in the total water variance equation is influential. This parameter affects the variance of in-cloud cloud water, which further influences microphysical process rates, such as autoconversion, and eventually low-cloud fraction. Furthermore, this study improves understanding of HOC behavior associated with parameter uncertainties and provides valuable insights for the interaction of macrophysics and microphysics.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC02-05CH11231; AC05-76RL01830
- OSTI ID:
- 1402218
- Alternate ID(s):
- OSTI ID: 1244807; OSTI ID: 1785819
- Report Number(s):
- PNNL-SA-106629
- Journal Information:
- Journal of Advances in Modeling Earth Systems, Journal Name: Journal of Advances in Modeling Earth Systems Vol. 7 Journal Issue: 3; ISSN 1942-2466
- Publisher:
- American Geophysical Union (AGU)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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