Tracer validation of air pollution dispersion models for waste-to-energy plants

SESSION C8 / 18 November 2020 / 14:45 - 15:15
Lorenzo Giovannini, University of Trento (IT)

A tracer experiment to validate air pollution dispersion models for the characterization of the environmental impact of a waste-to-energy plant in an Alpine valley

L. Giovannini, E. Tomasi, M. Falocchi, G. Antonacci, W. Tirler, D. Zardi

The simulation of pollutant dispersion over complex terrain is much more complicated than over flat areas, as dispersion processes are affected by atmospheric interactions with the orography at different spatial scales. Moreover, only few suitable observational datasets are available to be used as benchmark for testing dispersion models over complex terrain.

This contribution presents results from a study aiming at characterising dispersion processes from the incinerator of Bolzano, located in a basin in the Italian Alps. The experiment included a modelling chain, simulating both meteorological processes and pollutant dispersion, and field campaigns, performed to validate the simulated concentration fields against ground measurements of a gas tracer released from the incinerator stack. Two controlled releases of a passive gas tracer were performed in order to investigate the dispersion processes under two typical wintertime meteorological conditions. The first release was performed in the early morning, under stable atmosphere and northerly winds, while the second release was performed in the early afternoon, under weakly unstable atmosphere and southerly winds. Samples of ambient air were collected at several sites, and then analysed by means of a mass spectrometer with a detectability limit of 30 pptv.

The dispersion of the tracer was simulated by means of a modelling chain composed of both numerical weather prediction and pollutant dispersion models. In particular, the Weather Research and Forecasting (WRF) model was used to reproduce the meteorological fields, with a horizontal resolution of 300 m in the area of interest, and assimilating meteorological data from different ground weather stations, a temperature profiler, a SODAR and a Doppler wind LIDAR. The dispersion processes and the near-ground concentrations of the tracer were simulated with CALPUFF, a gaussian puff model, and with SPRAY-WEB, a lagrangian particle model. Both models were fed with data of emission rates and temperature, measured at the incinerator.

Results from the dispersion simulations were analysed and compared against tracer concentration measurements, in order to evaluate the model performance and to get valuable information for the use of the modelling chain for the characterization of the environmental impact of the incinerator.

Lorenzo Giovannini is assistant professor at the Department of Civil, Environmental and Mechanical Engineering of the University of Trento (Italy), where he received his PhD in Environmental Engineering with the thesis “Urban scale phenomena and boundary layer processes in mountain valleys”. His research activity focuses mainly on the analysis of atmospheric processes typical of mountainous regions and on the evaluation of microclimatic alterations induced by urban areas, by means of both experimental campaigns and numerical meteorological models. He is involved in different research projects, covering several aspects of applied meteorology, such as pollutant dispersion, support to agricultural practices, estimation of renewable energy sources and optimization of building energy consumption. On these topics he is author of several articles published in international peer-reviewed scientific journals.