The Cloud Feedback Model Intercomparison Project (CFMIP) contribution to CMIP6
- 1Met Office Hadley Centre, Exeter, UK
- 2LMD/IPSL, CNRS, Université Pierre and Marie Curie, Paris, France
- 3University of Washington, Seattle, USA
- 4Centre National de Recherches Météorologiques, Toulouse, France
- 5University of Colorado at Boulder, Boulder, USA
- 6Lawrence Livermore National Laboratory, Livermore, USA
- 7National Center for Atmospheric Research, Boulder, USA
- 8Royal Netherlands Meteorological Institute, De Bilt, The Netherlands
- 9University of Michigan, Ann Arbor, USA
- 10Max Planck Institute for Meteorology, Hamburg, Germany
- 11NASA Goddard Institute for Space Studies, New York, USA
- 12Atmosphere and Ocean Research Institute, Tokyo, Japan
Abstract. The primary objective of CFMIP is to inform future assessments of cloud feedbacks through improved understanding of cloud–climate feedback mechanisms and better evaluation of cloud processes and cloud feedbacks in climate models. However, the CFMIP approach is also increasingly being used to understand other aspects of climate change, and so a second objective has now been introduced, to improve understanding of circulation, regional-scale precipitation, and non-linear changes. CFMIP is supporting ongoing model inter-comparison activities by coordinating a hierarchy of targeted experiments for CMIP6, along with a set of cloud-related output diagnostics. CFMIP contributes primarily to addressing the CMIP6 questions
How does the Earth system respond to forcing? and
What are the origins and consequences of systematic model biases? and supports the activities of the WCRP Grand Challenge on Clouds, Circulation and Climate Sensitivity.
A compact set of Tier 1 experiments is proposed for CMIP6 to address this question: (1) what are the physical mechanisms underlying the range of cloud feedbacks and cloud adjustments predicted by climate models, and which models have the most credible cloud feedbacks? Additional Tier 2 experiments are proposed to address the following questions. (2) Are cloud feedbacks consistent for climate cooling and warming, and if not, why? (3) How do cloud-radiative effects impact the structure, the strength and the variability of the general atmospheric circulation in present and future climates? (4) How do responses in the climate system due to changes in solar forcing differ from changes due to CO2, and is the response sensitive to the sign of the forcing? (5) To what extent is regional climate change per CO2 doubling state-dependent (non-linear), and why? (6) Are climate feedbacks during the 20th century different to those acting on long-term climate change and climate sensitivity? (7) How do regional climate responses (e.g. in precipitation) and their uncertainties in coupled models arise from the combination of different aspects of CO2 forcing and sea surface warming?
CFMIP also proposes a number of additional model outputs in the CMIP DECK, CMIP6 Historical and CMIP6 CFMIP experiments, including COSP simulator outputs and process diagnostics to address the following questions.
How well do clouds and other relevant variables simulated by models agree with observations?
What physical processes and mechanisms are important for a credible simulation of clouds, cloud feedbacks and cloud adjustments in climate models?
Which models have the most credible representations of processes relevant to the simulation of clouds?
How do clouds and their changes interact with other elements of the climate system?