The CNRM Climate and Earth System Models for CMIP6

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Earth System Modeling 2018-2020
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24 February 2019
9 January 2021
This special collection deals with the description, evaluation, and analysis of the physical, chemical, and biogeochemical cores of all climate and Earth system models developed for the CMIP6 experiment jointly by CNRM and CERFACS. The CNRM-CERFACS group has a long history in developing these kinds of fully-coupled models and in participating in CMIP exercises. These papers describe advances made in climate modeling during the last decade by the CNRM-CERFACS group designed to perform: (1) fully-coupled ocean-land-atmosphere simulations (CMIP type); (2) stand-alone atmospheric experiments with prescribed sea surface temperature (AMIP type); (3) off-line ocean and/or land surface simulations driven by unbiased atmospheric variables (OMIP and/or LMIP types).[Photo Credit: Bernard Spragg, public domain.]
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Table of Contents

Open Access

Tracking Changes in Climate Sensitivity in CNRM Climate Models

D. Saint-Martin,  O. Geoffroy,  A. Voldoire,  J. Cattiaux,  F. Brient,  F. Chauvin,  M. Chevallier,  J. Colin,  B. Decharme,  C. Delire,  H. Douville,  J.-F. Guérémy,  E. Joetzjer,  A. Ribes,  R. Roehrig,  L. Terray,  S. Valcke, 
Key Points

  • The CNRM climate models contributing to Coupled Model Intercomparison Project phase 6 have a larger climate sensitivity than their CMIP5 predecessor

  • The climate sensitivity increase is the result of changes in the atmospheric component, through the dominant role of tropical cloud changes

  • The new convection scheme appears to play an important role in driving the cloud changes

Open Access

The CNRM Global Atmosphere Model ARPEGE-Climat 6.3: Description and Evaluation

Romain Roehrig,  Isabelle Beau,  David Saint-Martin,  Antoinette Alias,  Bertrand Decharme,  Jean-François Guérémy,  Aurore Voldoire,  Ahmat Younous Abdel-Lathif,  Eric Bazile,  Sophie Belamari,  Sebastien Blein,  Dominique Bouniol,  Yves Bouteloup,  Julien Cattiaux,  Fabrice Chauvin,  Matthieu Chevallier,  Jeanne Colin,  Hervé Douville,  Pascal Marquet,  Martine Michou,  Pierre Nabat,  Thomas Oudar,  Philippe Peyrillé,  Jean-Marcel Piriou,  David Salas y Mélia,  Roland Séférian,  Stéphane Sénési, 
Key Points

  • Version 6.3 of the ARPEGE-Climat atmospheric model includes an increased vertical resolution and a major update of the moist physics
  • Improvements include radiation, cloud and precipitation climatology, daily rainfall distribution, and water discharge at major river outlets
  • Weaknesses still include biases in low clouds and some dynamical fields, while the West African monsoon is a new model deficiency

Open Access

The Global Land Carbon Cycle Simulated With ISBA-CTRIP: Improvements Over the Last Decade

Christine Delire,  Roland Séférian,  Bertrand Decharme,  Ramdane Alkama,  Jean-Christophe Calvet,  Dominique Carrer,  Anne-Laure Gibelin,  Emilie Joetzjer,  Xavier Morel,  Matthias Rocher,  Diane Tzanos, 
Key Points

  • This paper documents the updates to the biogeochemical module of the ISBA-CTRIP land surface system for use in the CNRM-ESM 2-1 Earth system model
  • The newly represented processes are the leaching of carbon and transport of dissolved organic carbon to the ocean, fire with area burned and carbon emissions, and land cover changes
  • The largest improvements in the representation of net primary productivity are due to improved autotrophic respiration

Open Access

Present-Day and Historical Aerosol and Ozone Characteristics in CNRM CMIP6 Simulations

M. Michou,  P. Nabat,  D. Saint-Martin,  J. Bock,  B. Decharme,  M. Mallet,  R. Roehrig,  R. Séférian,  S. Sénési,  A. Voldoire, 
Key Points

  • The representations of aerosol and ozone in the CMIP6 CNRM-CM6-1 and CNRM-ESM2-1 models is described
  • Present-day and historical aerosol and ozone distributions are assessed, as well as their effective radiative forcing (ERF)
  • The present-day anthropogenic aerosol ERF (-1.10 W m urn:x-wiley:jame:media:jame21050:jame21050-math-0012 for CNRM-CM6-1) is sensitive to the interactivity of aerosols

Open Access

Evaluation of CNRM Earth System Model, CNRM-ESM2-1: Role of Earth System Processes in Present-Day and Future Climate

Roland Séférian,  Pierre Nabat,  Martine Michou,  David Saint-Martin,  Aurore Voldoire,  Jeanne Colin,  Bertrand Decharme,  Christine Delire,  Sarah Berthet,  Matthieu Chevallier,  Stephane Sénési,  Laurent Franchisteguy,  Jessica Vial,  Marc Mallet,  Emilie Joetzjer,  Olivier Geoffroy,  Jean-François Guérémy,  Marie-Pierre Moine,  Rym Msadek,  Aurélien Ribes,  Matthias Rocher,  Romain Roehrig,  David Salas-y-Mélia,  Emilia Sanchez,  Laurent Terray,  Sophie Valcke,  Robin Waldman,  Olivier Aumont,  Laurent Bopp,  Julie Deshayes,  Christian Éthé,  Gurvan Madec, 
Key Points

  • This study introduces CNRM-ESM2-1 and describes its set-up for CMIP6
  • Represented Earth system processes further impact the model response to external forcing than the model performance over present-day
  • Represented Earth system processes damp future warming by up to 10%

Open Access

Past Variability of Mediterranean Sea Marine Heatwaves

Sofia Darmaraki,  Samuel Somot,  Florence Sevault,  Pierre Nabat, 
Key Points

  • First time significant past trends of (sub)surface Mediterranean Marine heatwave characteristics are detected using a consistent framework
  • Subsurface events are seasonally shifted and on average longer and more severe than surface ones with different spatial hot spots
  • Record-breaking events are identified for the first time in 2012 and 2015 using a high-resolution coupled regional climate system model

Open Access

Evaluation of CMIP6 DECK Experiments With CNRM-CM6-1

A. Voldoire,  D. Saint-Martin,  S. Sénési,  B. Decharme,  A. Alias,  M. Chevallier,  J. Colin,  J.-F. Guérémy,  M. Michou,  M.-P. Moine,  P. Nabat,  R. Roehrig,  D. Salas y Mélia,  R. Séférian,  S. Valcke,  I. Beau,  S. Belamari,  S. Berthet,  C. Cassou,  J. Cattiaux,  J. Deshayes,  H. Douville,  C. Ethé,  L. Franchistéguy,  O. Geoffroy,  C. Lévy,  G. Madec,  Y. Meurdesoif,  R. Msadek,  A. Ribes,  E. Sanchez-Gomez,  L. Terray,  R. Waldman, 
Key Points

  • Description of CNRM-CM6-1 model components, their coupling, and tuning procedures are described
  • Historical simulations and DECK experiments are assessed
  • Preindustrial simulation is stable and mean climate and variability in historical runs is realistic

Free Access

Fast-Forward to Perturbed Equilibrium Climate

D. Saint-Martin,  O. Geoffroy,  L. Watson,  H. Douville,  G. Bellon,  A. Voldoire,  J. Cattiaux,  B. Decharme,  A. Ribes, 
Key Points

  • A simple method for estimating the equilibrium climate sensitivity is proposed
  • The method allows to simulate the stationary climate corresponding to any given radiative perturbation with a limited computational cost
  • The method can be applied to any atmosphere-ocean coupled climate model

Open Access

Evaluation of an Online Grid-Coarsening Algorithm in a Global Eddy-Admitting Ocean Biogeochemical Model

Sarah Berthet,  Roland Séférian,  Clément Bricaud,  Matthieu Chevallier,  Aurore Voldoire,  Christian Ethé, 
Key Points

  • The eddy-admitting (0.25°) model replicates observed physical-biogeochemical coupling, whereas the 1° horizontal resolution model does not
  • The computation cost of the eddy-admitting model is divided by 2.7 when using a coarse-grained grid for marine biogeochemistry
  • The coarse-grained solution inherits the key features of the 0.25° solution, including the physical-biogeochemical coupling

Open Access

Recent Changes in the ISBA-CTRIP Land Surface System for Use in the CNRM-CM6 Climate Model and in Global Off-Line Hydrological Applications

Bertrand Decharme,  Christine Delire,  Marie Minvielle,  Jeanne Colin,  Jean-Pierre Vergnes,  Antoinette Alias,  David Saint-Martin,  Roland Séférian,  Stéphane Sénési,  Aurore Voldoire, 
Key Points

  • Land Surface Modeling for global climate and hydrological applications
  • soil, snow, river, groundwater and floodwater processes

Open Access

Evaluating Marine Stratocumulus Clouds in the CNRM-CM6-1 Model Using Short-Term Hindcasts

Florent Brient,  Romain Roehrig,  Aurore Voldoire, 
Key Points

  • Short-term hindcasts help to disentangle timescales of marine stratocumulus cloud bias growth in the CNRM-CM6-1 model
  • Biases in low clouds are mostly related to errors in the subgrid distribution of temperature and humidity and the cloud-top entrainment
  • Along with single-columns models, short-term hindcasts are a complementary testbed for cloud parameterization development