Last update : February 2022


Since 2014 and thanks to the recent computer power increase, the CNRM climate group decided to use the Non-Hydrostatic limited area model AROME as a Convection-Permitting Regional Climate Model (CP-RCM).
The Meteo-France CP-RCM, CNRM-AROME, with a horizontal resolution of 2.5km and 60 vertical levels, inherits from most of the improvements of the Numerical Weather Prediction model AROME: small size of the mesh, detailed description of surfaces, better simulation of convective phenomena thanks to non-hydrostatic dynamics and resolving of deep convection, technically improved modelling of microphysics, clouds and turbulence. The physical parametrizations of the model come mostly from the research Meso-NH model whereas the dynamic core is the semi-lagrangian and semi-implicit spectral Non-Hydrostratic ALADIN one. The surface model used is the externalised surface interface SURFEX (Masson et al. 2013).
With a better representation of meteorological key processes highly linked with topography and various small-scale phenomena, significant improvements are expected for this new generation of climate models (Prein et al. 2015, Déqué et al. 2016, Berthou et al. 2020, Coppola et al. 2020, Fumière et al. 2020, Lucas-Picher at al. 2021).

 Simulations and versions

Currently, a two step driving strategy is chosen to provide the lateral boundary conditions to the CNRM-AROME model in order to limit the resolution jump and the coupling frequency is set to one hour. The intermediate model is CNRM-ALADIN model (Nabat et al. 2020) with a 12.5km resolution.

The first climate version of the model was based on the cycle 38t1 of AROME (Seity et al. 2011). The climate simulations were computed over the South-Eastern France and the studies focused on the added value of CNRM-AROME for extreme rainfall representation during autumn (Fumière et al. 2020) and on future climate change response of those events (Déqué et al. 2016, Fumière 2019).

The current version of CNRM-AROME is based on the cycle 41t1 (Termonia et al. 2018, Caillaud et al. 2021) with three important modifications since the first AROME climate simulations :
- the COMAD correction (Malardel and Ricard. 2015) had been added in order to limit overestimated precipitation and unrealistic divergent winds in the vicinity of convective clouds.
- the Town Energy Balance (TEB) model for urban modelling is activated (Masson 2000).
- the parameterisation of the turbulence fluxes above the sea, ECUME, is replaced by the COARE3 scheme.

The CNRM-AROME model allows the CNRM to participate to the European program CORDEX Flagship Pilot Study (FPS) on convection (2016-) and to the European project H2020-EUCP (EUropean Climate Prediction system, 2017-2022).

Two large domains have been defined for high resolution studies with CNRM-AROME41t1 : the common FPS Convection Pan-Alpine domain and the nearly twice larger North-West Europe domain. Recently, simulations have been performed on a domain centered on the Réunion island.

Fig : Left figure : Pan-Alpine domain at 2.5km (640*540 = 345600 points) - Central figure : North-West Europe domain at 2.5km (720*900 = 648000 points - Right figure : La Réunion domain at 2.5km (640*540 = 345600 points)

The AROME model is also used in climate mode by the HARMONIE-CLIMATE community (Belušic et al. 2020; Lind et al. 2020).

 Scientific applications

CNRM-AROME is a new climate model at CNRM and application fields will extend in the next few years. The first studies carried out with AROME at CNRM focus on :

  • the study of the added-value and limits of the CP-RCM AROME with respect to standart CORDEX RCM ALADIN-Climate using the hourly and kilometric observational database COMEPHORE (Fumière et al. 2020).
  • the evaluation and characterization of the variability of regional climate phenomena and extremes such as heavy precipitation events, using new climate evaluation tools as convective cell tracking (Caillaud et al. 2021).
  • the study of the regional climate change focusing on precipitation extremes in South-Eastern France (Déqué et al. 2016, Fumière 2019).
  • the contribution to the first-of-its-kind multi-model inter-comparison initiative of CP-RCM in the framework of both the CORDEX FPS convection and the european H2020 EUCP project (Coppola et al. 2020, Ban et al. 2021, Pichelli et al. 2021).
  • interactions between climate and cities at regional to local scales.
  • the study of Mediterranean islands’ climate.
  • lightnings.
  • the impacts of climate change on floods in France.

Other fields could be addressed by CNRM-AROME climate simulations : summer thunderstorms, orography-dependent weather processes, regional sea winds and intense air-sea fluxes, coastal areas,...

 Where to find CNRM-AROME data

Currently data are available on request.

 CNRM contibutors to the activity

Antoinette Alias, Erwan Brisson, Cécile Caillaud, Aude Lemonsu, Yohanna Michau, Philippe Lucas-Picher , Edith Virginia Cortès Hernandez, Nils Poncet, Samuel Somot

 Reference publications

Ban, N., Caillaud, C., Coppola, E., Pichelli,E., Sobolowski, S., Adinoli, M., Ahrens, B., Alias, A., Anders, I., Bastin, S., Belusic, D., Berthou, S., Brisson, E. et al. (2021) The first multi-model ensemble of regional climate simulations at kilometer-scale resolution, Part I: Evaluation of precipitation. Clim Dyn.

Caillaud, C., Somot, S., Alias, A., Bernard-Bouissières, I., Fumière, Q., Laurantin, O., Seity, Y., Ducrocq, V. (2021) Modelling Mediterranean heavy precipitation events at climate scale: an object-oriented evaluation of the CNRM-AROME convection-permitting regional climate model. Clim Dyn 56, 1717–1752.

Coppola, E., Sobolowski, S., Pichelli, E. et al. (2020) A first-of-its-kind multi-model convection permitting ensemble for investigating convective phenomena over Europe and the Mediterranean. Clim Dyn 55, 3–34.

Déqué M., Alias A., CNRM Research Report 2014, First attempt to simulate climate with AROME here.

Déqué M., Alias A., Somot S., Nuissier O. (2016) Climate change and extreme precipitation: the response by a convection-resolving model. Research activities in atmospheric and oceanic modelling. CAS/JSC Working group on numerical experimentation. Report No.46 (available at

Fumière, Q. (2019) Changement climatique et précipitations extrêmes : apport des modèles résolvant la convection. PhD thesis, Université Paul Sabatier, Toulouse III here

Fumière, Q., Déqué, M., Nuissier, O., Somot, S., Alias, A., Caillaud, C., Laurantin, O., Seity, Y. (2020) Extreme rainfall in Mediterranean France during the fall: added value of the CNRM-AROME convection-permitting regional climate model. Clim Dyn 55, 77–91.

Fumière, Q., Caillaud, C., CNRM Research Report 2019, Mediterranean events and climate change : contribution of CNRM-AROME here.

Lucas‐Picher, P., Argüeso, D., Brisson, E., Tramblay, Y., Berg, P., Lemonsu, A., Kotlarski, S., Caillaud, C. (2021). Convection‐permitting modeling with regional climate models: Latest developments and next steps. Wiley Interdisciplinary Reviews: Climate Change, 12(6), e731.

Pichelli, E., Coppola, E., Sobolowski, S., Ban, N., Giorgi, F., Stocchi P., Alias A., Belusic, D., Berthou, S., Caillaud, C., M. Cardoso, R. et al. (2021) The first multi-model ensemble of regional climate simulations at kilometer-scale resolution part 2: historical and future simulations of precipitation. Clim Dyn.

Termonia, P., Fischer, C., Bazile, E., Bouyssel, F., Brožková, R., Bénard, P., ... & Hamdi, R. (2018). The ALADIN System and its canonical model configurations AROME CY41T1 and ALARO CY40T1. Geoscientific Model Development, 11(1), 257.