The present activity represents the continuation of a three-year research commitment aimed at updating, validating, and developing meteorological and hydrological reanalysis datasets to support the national electrical system in identifying atmospheric and ground threats. Reanalysis products increasingly serve as powerful tools for understanding atmospheric threats, quantifying ground impacts from extreme events, and developing solutions to actively enhance the resilience of the national electrical system and prevent impacts from the intensification of these events due to climate change.

In the current research year, the updating of the Meteorological Reanalysis Italian Dataset (MERIDA) products has continued to cover recent years, along with the validation of existing products at various spatial and temporal scales. This is done to have a more comprehensive, reliable, and up-to-date reanalysis dataset. Additionally, in this research year, further applications of the MERIDA reanalysis datasets for studying various atmospheric threats have been refined and developed.

Regarding the threat of strong winds, the Atlante EOLico ItaliANo (AEOLIAN) has been used to extract maximum wind values for wind load mapping and to calculate the return periods of strong winds. This is done to quantify the threat and make initial assessments for a possible update of the reference regulations for wind load on overhead power lines, comparing the results with values in existing regulations.

Concerning wet snow phenomena and the formation of snow sleeves potentially damaging overhead transmission and distribution lines, the model to derive the expected sleeve load has been further refined. This involves updating sleeve load maps to the most recent period and conducting studies on sleeve load reconstruction for specific significant events reported by major electric utilities.

Work has also continued to create a new hydro-meteorological reanalysis dataset using the MERIDA HRES OI reanalysis forcing to drive a national-scale distributed hydrological model. This model simulates runoff in watercourses and inflow to major artificial reservoirs at a 250 m resolution, along with providing soil variables at a 4 km resolution (soil moisture, moisture, and heat flux) throughout Italy. In the current year, the necessary inputs for the hydrological model have been developed to appropriately and updately describe land use and land cover variables based on the most recent datasets available in the literature.

The calibration and validation phase has started, focusing on specific basins of national interest. Finally, in response to reports from electric utilities regarding the increasingly frequent occurrence of wildfires in summer, causing damage to overhead lines, a national-scale study has been undertaken. This study utilizes the state-of-the-art and information derived from the MERIDA reanalysis products to quantify the national-scale fire hazard through appropriate indices.

The Report is available on the Italian site