Submitted as: model experiment description paper 12 Nov 2021

Submitted as: model experiment description paper | 12 Nov 2021

Review status: this preprint is currently under review for the journal GMD.

Effects of forcing differences and initial conditions on inter-model agreement in the VolMIP volc-pinatubo-full experiment

Davide Zanchettin1, Claudia Timmreck2, Myriam Khodri3, Anja Schmidt4,5, Matthew Toohey6, Manabu Abe7, Slimane Bekki8, Jason Cole9, Shih-Wei Fang2, Wuhu Feng10, Gabriele Hegerl11, Ben Johnson12, Nicolas Lebas3, Allegra N. LeGrande13,14, Graham W. Mann10, Lauren Marshall5, Landon Rieger6, Alan Robock15, Sara Rubinetti1, Kostas Tsigaridis14,13, and Helen Weierbach16,17 Davide Zanchettin et al.
  • 1University Ca’ Foscari of Venice, Department of Environmental Sciences, Informatics and Statistics, Via Torino 155, 30172 Mestre, Italy
  • 2Max-Planck-Institute for Meteorology, Bundesstr. 53, 20146 Hamburg, Germany
  • 3Laboratoire d’Océanographie et du Climat: Expérimentations et Approches Numériques, Institut Pierre-Simon Laplace, Sorbonne Universités /IRD/CNRS/MNHN, Paris, France
  • 4Department of Geography, University of Cambridge,Cambridge, U.K.
  • 5Department of Chemistry, University of Cambridge, Cambridge, U.K.
  • 6Institute of Space and Atmospheric Studies, University of Saskatchewan, Canada
  • 7Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-ku, Yokohama 236-0001, Japan
  • 8Laboratoire Atmosphères, Milieux, Observations Spatiales, Institut Pierre-Simon Laplace, Sorbonne Université/CNRS/UVSQ, Paris, France
  • 9Environment and Climate Change Canada, Toronto, ON, Canada
  • 10University of Leeds, Leeds, UK
  • 11University of Edinburgh,Edinburgh, U.K.
  • 12Met Office Fitzroy Road EXETER EX1 3PB, U.K.
  • 13NASA Goddard Institute for Space Studies, New York, NY, USA
  • 14Center for Climate Systems Research, Columbia University, New York, NY, USA
  • 15Department of Environmental Sciences, Rutgers University, New Brunswick, NJ, USA
  • 16Earth and Environmental Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
  • 17Lamont Doherty Earth Observatory, Columbia University, New York, NY, USA

Abstract. This paper provides initial results from a multi-model ensemble analysis based on the volc-pinatubo-full experiment performed within the Model Intercomparison Project on the climatic response to volcanic forcing (VolMIP) as part of the sixth phase of the Coupled Model Intercomparison Project (CMIP6). The volc-pinatubo-full experiment is based on ensemble of volcanic forcing-only climate simulations with the same volcanic aerosol dataset across the participating models (the 1991–1993 Pinatubo period from the CMIP6-GloSSAC dataset). The simulations are conducted within an idealized experimental design where initial states are sampled consistently across models from the CMIP6-piControl simulation providing unperturbed pre-industrial background conditions. The multi-model ensemble includes output from an initial set of six participating Earth system models (CanESM5, GISS-E2.1-G, IPSL-CM6A-LR, MIROC-E2SL, MPI-ESM1.2-LR and UKESM1).

The results show overall good agreement between the different models on the global and hemispheric scale concerning the surface climate responses, thus demonstrating the overall effectiveness of VolMIP’s experimental design. However, small yet significant inter-model discrepancies are found in radiative fluxes especially in the tropics, that preliminary analyses link with minor differences in forcing implementation, model physics, notably aerosol-radiation interactions, the simulation and sampling of El Niño-Southern Oscillation (ENSO) and, possibly, the simulation of climate feedbacks operating in the tropics. We discuss the volc-pinatubo-full protocol and highlight the advantages of volcanic forcing experiments defined within a carefully designed protocol with respect to emerging modeling approaches based on large ensemble transient simulations. We identify how the VolMIP strategy could be improved in future phases of the initiative to ensure a cleaner sampling protocol with greater focus on the evolving state of ENSO in the pre-eruption period.

Davide Zanchettin et al.

Status: open (until 07 Jan 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CEC1: 'Comment on gmd-2021-372', Juan Antonio Añel, 26 Nov 2021 reply

Davide Zanchettin et al.

Davide Zanchettin et al.


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Short summary
This paper provides metadata and first analyses of the volc-pinatubo-full experiment of CMIP6-VolMIP. Results from six Earth system models reveal significant differences in radiative flux anomalies that trace back to different implementations of volcanic forcing. Surface responses are in contrast overall consistent across models, reflecting the large spread due to internal variability. A second phase of VolMIP shall consider both aspects toward improved protocol for volc-pinatubo-full.