title: The impact of parametrized convection on cloud feedback.
abstract: We investigate the sensitivity of cloud feedbacks to the use of convective parametrizations by repeating the CMIP5/CFMIP-2 AMIP/AMIP + 4K uniform sea surface temperature perturbation experiments with 10 climate models which have had their convective parametrizations turned off. Previous studies have suggested that differences between parametrized convection schemes are a leading source of inter-model spread in cloud feedbacks. We find however that 'ConvOff' models with convection switched off have a similar overall range of cloud feedbacks compared with the standard configurations. Furthermore, applying a simple bias correction method to allow for differences in present-day global cloud radiative effects substantially reduces the differences between the cloud feedbacks with and without parametrized convection in the individual models. We conclude that, while parametrized convection influences the strength of the cloud feedbacks substantially in some models, other processes must also contribute substantially to the overall inter-model spread. The positive shortwave cloud feedbacks seen in the models in subtropical regimes associated with shallow clouds are still present in the ConvOff experiments. Inter-model spread in shortwave cloud feedback increases slightly in regimes associated with trade cumulus in the ConvOff experiments but is quite similar in the most stable subtropical regimes associated with stratocumulus clouds. Inter-model spread in longwave cloud feedbacks in strongly precipitating regions of the tropics is substantially reduced in the ConvOff experiments however, indicating a considerable local contribution from differences in the details of convective parametrizations. In both standard and ConvOff experiments, models with less mid-level cloud and less moist static energy near the top of the boundary layer tend to have more positive tropical cloud feedbacks. The role of non-convective processes in contributing to inter-model spread in cloud feedback is discussed.
authors.affiliation: Met Office Hadley Centre (MOHC), Exeter, UK mark.webb@metoffice.gov.uk.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Webb
authors.affiliation: Met Office Hadley Centre (MOHC), Exeter, UK.
authors.forename: Adrian P
authors.initials: AP
authors.lastname: Lock
authors.affiliation: University of Washington (UW), Seattle, WA, USA.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Bretherton
authors.affiliation: Laboratoire de Météorologie Dynamique/Institute Pierre Simon Laplace (IPSL), Paris, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Bony
authors.affiliation: Canadian Centre for Climate Modelling and Analysis (CCCma), Victoria, British Columbia, Canada.
authors.forename: Jason N S
authors.initials: JN
authors.lastname: Cole
authors.affiliation: Laboratoire de Météorologie Dynamique/Institute Pierre Simon Laplace (IPSL), Paris, France.
authors.forename: Abderrahmane
authors.initials: A
authors.lastname: Idelkadi
authors.affiliation: Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Kang
authors.affiliation: Meteorological Research Institute (MRI), Tsukuba, Ibaraki Prefecture, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Koshiro
authors.affiliation: Meteorological Research Institute (MRI), Tsukuba, Ibaraki Prefecture, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kawai
authors.affiliation: National Institute for Environmental Studies (NIES), Tsukuba, Ibaraki Prefecture, Japan.
authors.forename: Tomoo
authors.initials: T
authors.lastname: Ogura
authors.affiliation: Centre National de Recherches Météorologiques (CNRM), Toulouse, France.
authors.forename: Romain
authors.initials: R
authors.lastname: Roehrig
authors.affiliation: Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea.
authors.forename: Yechul
authors.initials: Y
authors.lastname: Shin
authors.affiliation: Max Planck Institute for Meteorology (MPI-M), Hamburg, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Mauritsen
authors.affiliation: University of New South Wales (UNSW), Sydney, New South Wales, Australia.
authors.forename: Steven C
authors.initials: SC
authors.lastname: Sherwood
authors.affiliation: Laboratoire de Météorologie Dynamique/Institute Pierre Simon Laplace (IPSL), Paris, France.
authors.forename: Jessica
authors.initials: J
authors.lastname: Vial
authors.affiliation: Atmosphere and Ocean Research Institute (AORI), Chiba, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: University of Washington (UW), Seattle, WA, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Woelfle
authors.affiliation: Geophysical Fluid Dynamics Laboratory (GFDL), Princeton, NJ, USA.
authors.forename: Ming
authors.initials: M
authors.lastname: Zhao
keywords: climate; cloud; convection; feedback; parametrization