The Meso-NH atmospheric model – Laboratoire d'Aerologie

What is Meso-NH ?

Meso-NH (https://mesonh.cnrs.fr) is the non-hydrostatic mesoscale atmospheric model developed by the French research community. It has been labeled as a National Observation Service-Community Code (SNO-CC) by the National Institute of Universe Sciences (INSU) of the CNRS since 1997 and has been part of CLIMERI-France since 2025.

Meso-NH enables the simulation of a wide range of atmospheric phenomena, from planetary scales (thousands of kilometers) down to turbulent eddies (a few meters). With its advanced set of physical and chemical parameterizations, it facilitates the study of aerosols, clouds, precipitation, radiation, chemistry, and lightning in diverse meteorological phenomena such as storms, cyclones, and fog.

The model is also designed to investigate surface-atmosphere interactions and the impacts of environmental changes in urban, forest, and hydrological settings. Additionally, Meso-NH is coupled with wind turbine models, wildfire propagation models, wave models, and ocean models.

First 5-h of a Meso-NH simulation of Hector the convector, which forms nearly every afternoon during the early and late wet season on the Tiwi Islands north of Darwin in Northern Australia. The simulation runs with a 200-m grid spacing using 8192 cores of Turing, a CNRS/IDRIS BlueGene supercomputer. The animation shows the cloud enveloppe of Hector every minute. More on http://dx.doi.org/10.1002/asl2.534

What does the LAERO do for Meso-NH?

The LAERO hosts part of the SNO CC Meso-NH team, whose mission is to facilitate access to the model by managing its evolving codebase, assisting users and developers, and fostering community engagement through training sessions and scientific workshops. Jean-Pierre Chaboureau is the head of the National Observation Service – Community Code Meso-NH (SNO CC Meso-NH) at INSU, and the LAERO-based members of the SNO CC Meso-NH team are Thibaut Dauhut, Juan Escobar, Joris Pianezze end Philippe Wautelet. The other part of the SNO CC Meso-NH team is located at CNRM.

What is Meso-NH used for at LAERO?

At LAERO, Meso-NH serves as a core research tool for studying atmospheric processes across various scales. Specifically, it is used to:

Investigate atmospheric boundary layer dynamics: Turbulence, convection, land-atmosphere exchanges, sea breezes, valley winds, orographic effects, etc.
Study the life cycle of storms and tropical cyclones: Turbulence, convection, ocean-wave-atmosphere interactions, sea spray, marine aerosols, etc.
Analyze clouds and convection: Cloud formation and evolution, thunderstorms, precipitation, aerosol-cloud-radiation interactions, convective organization, etc.
Simulate and interpret field campaigns: Supporting or complementing observations (radar, lidar, balloons, research aircraft, drones) to better understand observed phenomena.
Examine the transport and transformation of atmospheric tracers: Aerosols, reactive gases, pollution, plumes (urban, industrial, wildfires), using a coupled dynamics-chemistry approach.
Studying atmospheric boundary layer dynamics: Turbulence, convection, land-atmosphere exchanges, sea breezes, valley winds, orographic effects, etc.
Develop and evaluate physical parameterizations: Turbulence, microphysics, surface processes, radiation, atmospheric chemistry, often in collaboration with other models or observations.

In summary, at LAERO, Meso-NH is used to gain a detailed understanding of atmospheric processes, bridge the gap between observations and theory, and test new physical representations of the atmosphere. These advancements are subsequently integrated into Météo-France’s operational model, thanks to their shared physics framework.

Training

A 4-day training session is organized twice a year in Toulouse, France:

The November session is held in-person only, with presentations in French (slides and materials are in English).
The March session is offered in a hybrid format (in-person + remote), with presentations in English.

For more information, visit the mesonh.cnrs .fr.

History

Meso-NH was developed in 1993 as a collaborative project between the mesoscale atmospheric modeling teams at the Centre National de Recherche Météorologique (CNRM, Météo-France’s research laboratory) and the Laboratoire d’Aérologie (LAERO). In 2023, Meso-NH celebrated its 30th anniversary and is now used by a broad community of nearly 140 researchers across 20 teams, including atmospheric scientists, hydrologists, and more. It was also one of the first models to run on the AdAstra supercomputer in 2023.