CGILS: Results from the first phase of an international project to understand the physical mechanisms of low cloud feedbacks in single column models

AMS Citation:
Zhang, M., and Coauthors, 2013: CGILS: Results from the first phase of an international project to understand the physical mechanisms of low cloud feedbacks in single column models. Journal of Advances in Modeling Earth Systems, 5, 826-842, doi:10.1002/2013MS000246.
Date:2013-12-01
Resource Type:article
Title:CGILS: Results from the first phase of an international project to understand the physical mechanisms of low cloud feedbacks in single column models
Abstract: CGILS—the CFMIP-GASS Intercomparison of Large Eddy Models (LESs) and single column models (SCMs)—investigates the mechanisms of cloud feedback in SCMs and LESs under idealized climate change perturbation. This paper describes the CGILS results from 15 SCMs and 8 LES models. Three cloud regimes over the subtropical oceans are studied: shallow cumulus, cumulus under stratocumulus, and well-mixed coastal stratus/stratocumulus. In the stratocumulus and coastal stratus regimes, SCMs without activated shallow convection generally simulated negative cloud feedbacks, while models with active shallow convection generally simulated positive cloud feedbacks. In the shallow cumulus alone regime, this relationship is less clear, likely due to the changes in cloud depth, lateral mixing, and precipitation or a combination of them. The majority of LES models simulated negative cloud feedback in the well-mixed coastal stratus/stratocumulus regime, and positive feedback in the shallow cumulus and stratocumulus regime. A general framework is provided to interpret SCM results: in a warmer climate, the moistening rate of the cloudy layer associated with the surface-based turbulence parameterization is enhanced; together with weaker large-scale subsidence, it causes negative cloud feedback. In contrast, in the warmer climate, the drying rate associated with the shallow convection scheme is enhanced. This causes positive cloud feedback. These mechanisms are summarized as the "NESTS" negative cloud feedback and the "SCOPE" positive cloud feedback (Negative feedback from Surface Turbulence under weaker Subsidence—Shallow Convection PositivE feedback) with the net cloud feedback depending on how the two opposing effects counteract each other. The LES results are consistent with these interpretations.
Subject(s):low cloud feedbacks, CGILS, single column models, large eddy models
Peer Review:Refereed
Copyright Information:Copyright 2013 American Geophysical Union.
OpenSky citable URL: ark:/85065/d70z746s
Publisher's Version: 10.1002/2013MS000246
Author(s):
  • Minghua Zhang
  • Christopher Bretherton
  • Peter Blossey
  • Phillip Austin
  • Julio Bacmeister - NCAR/UCAR
  • Sandrine Bony
  • Florent Brient
  • Suvarchal Cheedela
  • Anning Cheng
  • Anthony Del Genio
  • Stephan De Roode
  • Satoshi Endo
  • Charmaine Franklin
  • Jean-Christophe Golaz
  • Cecile Hannay - NCAR/UCAR
  • Thijs Heus
  • Francesco Isotta
  • Jean-Louis Dufresne
  • In-Sik Kang
  • Hideaki Kawai
  • Martin Köhler
  • Vincent Larson
  • Yangang Liu
  • Adrian Lock
  • Ulrike Lohmann
  • Marat Khairoutdinov
  • Andrea Molod
  • Roel Neggers
  • Philip Rasch
  • Irina Sandu
  • Ryan Senkbeil
  • A. Siebesma
  • Colombe Siegenthaler-Le Drian
  • Bjorn Stevens
  • Max Suarez
  • Kuan-Man Xu
  • Knut von Salzen
  • Mark Webb
  • Audrey Wolf
  • Ming Zhao
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