Preprints
https://doi.org/10.5194/gmd-2020-413
https://doi.org/10.5194/gmd-2020-413

Submitted as: model description paper 21 Dec 2020

Submitted as: model description paper | 21 Dec 2020

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

EC-Earth3-AerChem, a global climate model with interactive aerosols and atmospheric chemistry participating in CMIP6

Twan van Noije1, Tommi Bergman1,2, Philippe Le Sager1, Declan O'Donnell2, Risto Makkonen2,3, María Gonçalves-Ageitos4,5, Ralf Döscher6, Uwe Fladrich6, Jost von Hardenberg7, Jukka-Pekka Keskinen2,3, Hannele Korhonen2, Anton Laakso8, Stelios Myriokefalitakis9, Pirkka Ollinaho2, Carlos Pérez García-Pando4,10, Thomas Reerink1, Roland Schrödner11,a, Klaus Wyser6, and Shuting Yang12 Twan van Noije et al.
  • 1Royal Netherlands Meteorological Institute, De Bilt, Netherlands
  • 2Climate System Research, Finnish Meteorological Institute, Helsinki, Finland
  • 3Institute for Atmospheric and Earth System Research, Faculty of Science, University of Helsinki, Helsinki, Finland
  • 4Barcelona Supercomputing Center, Barcelona, Spain
  • 5Technical University of Catalonia, Barcelona, Spain
  • 6Swedish Meteorological and Hydrological Institute, Norrköping, Sweden
  • 7Institute of Atmospheric Sciences and Climate, National Research Council, Turin, Italy
  • 8Atmospheric Research Centre of Eastern Finland, Finnish Meteorological Institute, Kuopio, Finland
  • 9Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Athens, Greece
  • 10ICREA, Catalan Institution for Research and Advanced Studies, Barcelona, Spain
  • 11Centre for Environmental and Climate Research, Lund University, Lund, Sweden
  • 12Danish Meteorological Institute, Copenhagen, Denmark
  • anow at: Leibniz Institute for Tropospheric Research, Leipzig, Germany

Abstract. This paper documents the global climate model EC-Earth3-AerChem, one of the members of the EC-Earth3 family of models participating in the Coupled Model Intercomparison Project phase 6 (CMIP6). EC-Earth3-AerChem has interactive aerosols and atmospheric chemistry and contributes to the Aerosols and Chemistry Model Intercomparison Project (AerChemMIP). In this paper, we give an overview of the model and describe in detail how it differs from the other EC-Earth3 configurations, and what the new features are compared to the previously documented version of the model (EC-Earth 2.4). We explain how the model was tuned and spun up under pre-industrial conditions and characterize the model's general performance on the basis of a selection of coupled simulations conducted for CMIP6. The mean energy imbalance at the top of the atmosphere in the pre-industrial control simulation is −0.10 ± 0.25 W m−2 and shows no significant drift. The corresponding mean global surface air temperature is 14.05 ± 0.16 °C, with a small drift of −0.075 ± 0.009 °C per century. The model's effective equilibrium climate sensitivity is estimated at 3.9 °C and its transient climate response at 2.1 °C. The CMIP6 historical simulation displays spurious interdecadal variability in Northern Hemisphere temperatures, resulting in a large spread among ensemble members and a tendency to underestimate observed annual surface temperature anomalies from the early 20th century onwards. The observed warming of the Southern Hemisphere is well reproduced by the model. Compared to the ERA5 reanalysis of the European Centre for Medium-Range Weather Forecasts, the ensemble mean surface air temperature climatology for 1995–2014 has an average bias of −0.86 ± 0.35 °C in the Northern Hemisphere and 1.29 ± 0.05 °C in the Southern Hemisphere. The Southern Hemisphere warm bias is largely caused by errors in shortwave cloud radiative effects over the Southern Ocean, a deficiency of many climate models. Changes in the emissions of near-term climate forcers (NTCFs) have significant climate effects from the 20th century onwards. For the SSP3-7.0 shared socio-economic pathway, the model gives a global warming at the end of the 21st century (2091–2100) of 4.9 °C above the pre-industrial mean. A 0.5 °C stronger warming is obtained for the AerChemMIP scenario with reduced emissions of NTCFs. With concurrent reductions of future methane concentrations, the warming is projected to be reduced by 0.5 °C.

Twan van Noije et al.

 
Status: open (until 15 Feb 2021)
Status: open (until 15 Feb 2021)
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Twan van Noije et al.

Twan van Noije et al.

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This paper documents the global climate model EC-Earth3-AerChem, one of the members of the EC-Earth3 family of models participating in the Coupled Model Intercomparison Project phase 6 (CMIP6). We describe the model in detail and provide information about the applied tuning and spin-up procedures. The model's performance is characterized using coupled simulations conducted for CMIP6. The model has an effective equilibrium climate sensitivity of 3.9 °C and a transient climate response of 2.1 °C.