What is WRF
WRF (Weather Research and Forecasting model, Skamarock et al., 2019) is a mesoscale numerical weather prediction system designed for both atmospheric research and operational forecasting applications, developed at the National Center for Atmospheric Research (NCAR), Boulder, CO, U.S.A. It relies on two dynamical cores: the Advanced Research WRF (ARW) and the NCEP Non-hydrostatic Mesoscale Model (NMM). Both are based on the flux form of the Boussinesq, non-hydrostatic Navier–Stokes equations that resolve advection, viscosity, pressure gradients, and Coriolis acceleration. The WRF-ARW, the most widely used dynamical core, is a fully compressible, nonhydrostatic model employing a hybrid terrain-following hydrostatic pressure vertical coordinate. It uses an Arakawa C-grid for spatial discretization and a Runge-Kutta time integration scheme.
A major strength of WRF-ARW is its modular architecture which offers flexibility in physical parameterizations, with a wide range of options for microphysics, cumulus convection, planetary boundary layer processes, surface-atmosphere interactions, and radiation. This modularity enables studies of atmospheric processes from microscale weather events, such as thunderstorms and sea breezes, to larger-scale phenomena, including monsoons and tropical cyclones.
Due to its open-source nature, broad community support, and continuous development, the WRF-ARW has become a cornerstone tool in both research and operational meteorology, widely applied in weather prediction, climate studies, renewable energy, and air quality modeling.
How does CMCC use WRF?
SEAS – WRF is a component of a regional ocean-atmosphere coupled model developed at CMCC, named SEAS. It has been implemented on the Southern European Seas, and the domain spans from the Eastern Atlantic Ocean to the Black Sea, and from Northern Africa to Northern Europe. Even though the focus of this model is the improvement of the ocean dynamics forecasting in the Southern European Seas, the extension of the domain was driven by the atmospheric component, whose implementation must be able to properly downscale the atmospheric perturbations coming from the Northern Atlantic. The novelty of this implementation is that the two components share the same computation grid at 1/24 degrees resolution (2.8-4.2 km), so that WRF is run in non-hydrostatic mode and this configuration is quasi- convection permitting.
The coupling is performed through the OASIS3-MCT coupler, which every 30 minutes performs the traditional ocean-driven coupling. The atmospheric fluxes of mass (evaporation-precipitation), energy (turbulent and radiative fluxes) and momentum (wind stress) are calculated in WRF and passed to the ocean component, which in turn provides the Sea Surface Temperature and currents
The model initialized by oceanic (merge of several analyses) and atmospheric analysed (ECMWF-IFS), has been run in forecast mode and the oceanic outputs are currently objective of validation to assess whether an improvement of the forecast skills is achievable.
WRF_6km@CMCC- The WRF_6km@CMCC (Verri et al. 2024) is a high-resolution (about 6 km resolution and 6h frequency) atmospheric model based on the WRF-ARW core in its version 4.4.1 It is 2way coupled with both the NOAM-ML land surface model and the WRFHydro modular system solving the hydrology-hydraulics processes over about 145 catchments surrounding the Adriatic Sea at 600m resolution and 1h freq. WRF_6km@CMCC is currently used to perform long term projections of the coastal water cycle over the Adratiatic region working in coupled mode with the general circulation model NEMO with a resolution ratio 1:3, i.e. NEMO horizontal res is about 2km and air-sea fluxes are solved at the mesoscale
WRF_2km@CMCC – The WRF_2km@CMCC (Manco et al., 2023) is a high-resolution (2 km) atmospheric model based on the WRF-ARW core. At CMCC, it is used in operational mode within the SILVANUS project, with focus domains over Apulia, Sardinia, and Portugal, forced by GFS data. The same configuration has also been driven by IFS analyses to perform historical simulations.
WRF_500m@CMCC – The WRF_500m@CMCC is a very high-resolution (500 m) two-way nested configuration of the WRF_2km@CMCC model. It has been implemented at CMCC over the Apulia Region pilot site and driven by IFS analyses for historical simulations at sub-kilometric scale.
References
Manco, I., De Lucia, C., Repola, F., Fedele, G., & Mercogliano, P. (2023). A Comparative Performance Study of WRF, COSMO and ICON Atmospheric Models for the Italian Peninsula at Very High Resolution. Tethys: revista meteorología y climatología mediterránea, (20), 1-20.
Verri, G, L. Furnari, M. Gunduz, A. Senatore, V. Santos da Costa, A. De Lorenzis, G. Fedele, I. Manco, L. Mentaschi, E. Clementi, G. Coppini, P. Mercogliano, G. Mendicino, N. Pinardi, (2024). Climate projections of the Adriatic Sea: the role of river release, Frontiers in Climate