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Title: A sensitivity analysis of cloud properties to CLUBB parameters in the single-column Community Atmosphere Model (SCAM5)

In this study, we investigate the sensitivity of simulated shallow cumulus and stratocumulus clouds to selected tunable parameters of Cloud Layers Unified by Binormals (CLUBB) in the single column version of Community Atmosphere Model version 5 (SCAM5). A quasi-Monte Carlo (QMC) sampling approach is adopted to effectively explore the high-dimensional parameter space and a generalized linear model is adopted to study the responses of simulated cloud fields to tunable parameters. One stratocumulus and two shallow convection cases are configured at both coarse and fine vertical resolutions in this study.. Our results show that most of the variance in simulated cloud fields can be explained by a small number of tunable parameters. The parameters related to Newtonian and buoyancy-damping terms of total water flux are found to be the most influential parameters for stratocumulus. For shallow cumulus, the most influential parameters are those related to skewness of vertical velocity, reflecting the strong coupling between cloud properties and dynamics in this regime. The influential parameters in the stratocumulus case are sensitive to the choice of the vertical resolution while little sensitivity is found for the shallow convection cases, as eddy mixing length (or dissipation time scale) plays a more important role andmore » depends more strongly on the vertical resolution in stratocumulus than in shallow convections. The influential parameters remain almost unchanged when the number of tunable parameters increases from 16 to 35. This study improves understanding of the CLUBB behavior associated with parameter uncertainties.« less
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [2] ;  [2] ;  [4] ;  [2] ;  [2] ;  [5]
  1. Atmosphere Science and Global Change Division, 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
  2. Atmosphere Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA
  3. Department of Mathematical Sciences, University of Wisconsin-Milwaukee, Milwaukee Wisconsin USA
  4. National Center for Atmospheric Research, Boulder Colorado USA
  5. 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
Publication Date:
OSTI Identifier:
1168894
Report Number(s):
PNNL-SA-101254
Journal ID: ISSN 1942-2466; KP1703020; KJ0403000
Grant/Contract Number:
AC05-76RL01830
Type:
Accepted Manuscript
Journal Name:
Journal of Advances in Modeling Earth Systems
Additional Journal Information:
Journal Volume: 6; Journal Issue: 3; Journal ID: ISSN 1942-2466
Publisher:
American Geophysical Union (AGU)
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; shallow cumulus and stratocumulus clouds; Cloud Layers Unified by Binormals (CLUBB); Community Atmosphere Model version 5 (SCAM5)