The overall objective of the modeling activities to support the insulator contamination studies conducted in the 2019-2021 three-year period of System Research was to develop increasingly precise parameterizations of the insulator contamination phenomena to be introduced into the air quality forecasting modeling chain of SMOKE_WRF_CAMx used by RSE. These activities contributed to making the modeling system an increasingly suitable tool for the simulation of critical episodes of insulator contamination, also allowing the Italian territory to be characterized in terms of insulator pollution risk. The studies conducted over the above-mentioned three-year period were both modeling and experimental in nature.
The modeling updates tested in their first version in 2021 concerned the modules for the reconstruction of natural sources (sea spray), the module for the reconstruction of dry deposition at the isolator scale, and the formulation of the relationship between deposited mass and conductance.
With reference to the simulation of sea spray emission, some configurations were compared with the aim of identifying the most suitable one for the present case study, also taking explicitly into account the processes linked to wave movement.
Regarding the deposition process, a simplified closed-form solution has been derived for the flow of atmospheric particulate matter (PM) deposited on electrical insulators. The closure of the mathematical model was obtained through a 4D regression procedure on the results of numerical simulations performed using a stochastic Lagrangian model. This solution was then used for preliminary estimates of the deposition flow, as a simplified sub-grid parameterization as an alternative to the DePaSITIA library (RSE SpA).
Finally, in collaboration with the Department of Environmental and Earth Sciences (Dipartimento di Scienze dell’Ambiente e della Terra, DISAT) of the Università degli Studi di Milano Bicocca (UNIMIB), a smog chamber dataset was developed which describes the evolution of the deposited mass as thermodynamic parameters (T, RH) vary. The comparison between the experimental data and data reconstructed using the ISORROPIA model indicates that the experimental relationship between conductance and aqueous content of the deposited mass can serve as a reference for a preliminary version of the module describing the thermodynamic behavior of the deposit.