This paper describes an experimental protocol focused on sudden stratospheric warmings to be carried out by subseasonal forecast modeling centers. These will allow for inter-model comparisons of these major disruptions to the stratospheric polar vortex and their impacts on the near-surface flow. The protocol will lead to new insights into the contribution of the stratosphere to subseasonal forecast skill and new approaches to the dynamical attribution of extreme events.

This work presents the on-line coupled meteorology-chemistry transport model BOLCHEM. The paper describes the meteorological and chemical modules, and presents simulation results on the European domain for one year run. For all considered pollutants (O₃, NO₂, PM₁₀, PM_2.5) the model performances are close to those achieved by the current state-of-the-art model system dedicated to air quality study, e.g. Copernicus CAMS products.

The probabilistic evaluation of 2 m temperature forecast of about one year of monthly ensemble forecasts, issued on a monthly basis, is provided. The ranked probability skill score, averaged over all the available cases, shows that the system has a residual predictive skill beyond week 2 on some peculiar regions. Reliability diagrams show that, in general, the probability forecasts of above-normal observed temperature are more reliable than below-normal temperature.

Quality of wind prediction is of great importance since a good wind forecast allows the prediction of available wind power, improving the penetration of renewable energies into the energy market. This work shows the application of a technique to improve wind forecasting. The study area is southern Italy.

In the HyMeX framework, an intercomparison study of two different configurations of the ISPRA hydro-meteo-marine forecasting system (SIMM) has been performed to assess the forecast skill in predicting high precipitations and very intense storm surges over the northern Adriatic Sea (acqua alta). The results show an objective added value of the use of high-resolution meteorological models, and they suggest the opportunity to develop a time-lagged multi-model ensemble for the acqua alta prediction.