HARMONIE-AROME

HARMONIE-AROME
Name	HARMONIE-AROME
Developer	European Meteorological community
Latest release	2019-2023 cycle
Programming language	Fortran, C, Python
Operating system	Linux
License	Open-source (ECMWF-related agreements)

HARMONIE-AROME

HARMONIE-AROME is a convection-permitting, limited-area numerical weather prediction system used across Europe and beyond. It integrates dynamical cores, physical parameterizations, data assimilation, and verification tools to produce short-range forecasts for meteorological services such as Météo-France, KNMI, Met Éireann, SMHI, and DMI. The system is tightly connected with research from ECMWF, ALADIN Consortium, HIRLAM Consortium, Météo-France Centre National de Recherches Météorologiques (CNRM), and academic groups at institutions like University of Reading, ETH Zurich, and Uppsala University.

Overview

HARMONIE-AROME operates at grid spacings commonly between 1.3 km and 4.5 km and is designed for short-range forecasts from minutes to 48 hours, supporting hazards monitored by agencies such as Met Office, Deutscher Wetterdienst, Rijkswaterstaat, Irish Aviation Authority, and Norwegian Meteorological Institute. Its architecture derives from the mesoscale system family that includes ALADIN, ARPEGE, and shares development history with projects involving ECMWF Reanalysis, Copernicus, and regional initiatives like UERRA. Users employ it for nowcasting, ensemble approaches linked to EPS frameworks, and coupling with ocean or hydrology models from groups such as SMHI Hydrology and Deltares.

Development and Modeling Framework

The modeling framework is the result of collaborative work among consortia including ALADIN, HIRLAM, EUMETNET, and research teams at Météo-France, KNMI, and DMI. The dynamical core uses non-hydrostatic equations with forward-backward and semi-implicit schemes developed in parallel with numerical methods studied at University of Oxford, Imperial College London, and Technical University of Denmark. Code governance and version control practices were influenced by software engineering groups at CERN and EMC efforts linked to ECMWF. Data assimilation modules implement 3D-Var and hybrid variational-ensemble methods akin to systems developed at Met Office and Deutscher Wetterdienst.

Physics and Parameterizations

HARMONIE-AROME includes high-resolution microphysics schemes and boundary-layer parameterizations developed and evaluated alongside research from Météo-France CNRM, INRAE, CNRS, and university groups at Sorbonne Université and Université de Montréal. Parameterizations cover cloud microphysics, aerosol-cloud interactions, radiation transfer models compared with work at NASA Goddard, NOAA GFDL, and ECMWF Radiation teams. Surface schemes interface with land-surface models originating from SURFEX, ISBA, and coupling investigations involving JRC and SMHI. Convection is largely resolved at convection-permitting scales but retains parameterized turbulence and subgrid processes informed by studies from Princeton University and Max Planck Institute for Meteorology.

Operational Implementation and Use

Operational centers deploy HARMONIE-AROME in production chains managed by agencies such as Météo-France, KNMI, Met Éireann, SMHI, DMI, and regional services like Met Éireann, Icelandic Meteorological Office, and Estonian Weather Service. Implementations often couple HARMONIE-AROME with data streams from EUMETSAT, Copernicus Sentinel, GNSS networks, and conventional observations from WMO stations. Workflow orchestration and high-performance computing rely on systems administered by Arctic Region Supercomputing Center, CSC — IT Center for Science, and national centers like Météo-France computing center and KNMI HPC. Post-processing integrates tools and products from MET Norway, OOFEM-style scripts, and visualization systems used by ECMWF and EUMETNET members.

Performance and Verification

Performance assessment uses deterministic and ensemble metrics developed alongside verification research at ECMWF, Met Office, DWD, KNMI, and academic groups at University of Oxford and University of Reading. Verification focuses on precipitation, wind, temperature, and boundary-layer variables using datasets from E-OBS, MESCAL, OPERA, CEOP, and national observation networks such as UK Met Office surface network, Royal Netherlands Meteorological Institute network, and Icelandic synoptic stations. Studies published with partners like JGR, Tellus A, and Weather and Forecasting compare HARMONIE-AROME with models including COSMO, ICON, WRF, and Arome-France configurations for case studies such as Storm Ciara, Storm Dennis, and convective outbreaks documented by SESAR projects.

Applications and Case Studies

HARMONIE-AROME has been applied to flash-flood forecasting in collaboration with JRC and Deltares, wind energy forecasting with partners like TenneT and Vattenfall, and aviation forecasting used by IATA and national air traffic services. Case studies include high-impact weather events documented in coordination with Copernicus Emergency Management Service, hydrometeorological coupling projects with SMHI Hydrology and Irish Flood Forecasting Service, and urban meteorology experiments in cities like Paris, Amsterdam, and Stockholm. Scientific investigations have integrated HARMONIE-AROME into climate downscaling initiatives tied to CMIP6, CORDEX, and impact assessments for infrastructure planning by European Commission agencies.

Category:Numerical weather prediction