The formation of ice sleeves on overhead power lines, heavy snowfall, and strong wind gusts can cause severe infrastructure damage and, consequently, prolonged disruptions to the National Transmission Grid.

To define action plans aimed at increasing the Grid’s resilience, it is essential to have maps of the probability of these phenomena occurring, from which future variations in the national territory due to climate change can be inferred.

Such maps have been produced by processing the results of 11 Euro-CORDEX regional climate models with a spatial resolution of approximately 12 km, for the period 1986-2060, assuming a business-as-usual scenario (RCP8.5 emission scenario).

Additionally, MERIDA meteorological reanalysis data, with a spatial resolution of 7 km x 7 km, available for the period 1986-2019, were used to perform bias correction on the climate models using the Equidistant Quantile Mapping technique.

MERIDA was also used to develop a simplified formulation of the Makkonen model to describe, with daily weather data (typical of climate models), the growth of ice sleeves on high-voltage lines, a phenomenon that occurs during wet-snow conditions. Moreover, MERIDA was used to develop the “Snow” model, aimed at estimating the snow load on the ground. After validation, these new codes were applied to the climate models to quantify phenomena up to 2060 and derive future scenarios. Probability maps were created to describe expected values at different time horizons (2020, 2030, 2040, and 2050), applying Generalized Extreme Values (GEV) statistical techniques.

The results indicate that snow-related phenomena will generally decrease due to global warming. However, while cases of ice sleeve loads are expected to diminish at mid-low altitudes, such events may intensify in alpine regions that have previously been spared, as temperatures between -1.5 and +2°C will become more likely and will facilitate the occurrence of wet snow.

Regarding wind, RSE played a supervisory role in analyzing the CESMLENS numerical simulations provided by Terna, conducted under the RCP 8.5 scenario, which indicates no significant changes in strong wind events for our country.