Measurement and Modeling of Local Circulation Patterns and Pollutant Dispersion from a Waste Incinerator in the Basin of Bolzano in the Italian Alps

Results are presented from the Bolzano Tracer Experiment (B-TEX) which was perfomed on 14 February 2017 near the city of Bolzano in the Eastern Italian Alps. The city lies in a basin, surrounded by high alpine crests, where four triburary valleys join. The experiment was part of a project aiming at the optimal design of a permanent air-quality-station network for monitoring long-term effect of pollutants emitted by the incinerator, as well as to outline possible scenarios of pollutant dispersion under accidental release. The experiment included two 1-h-long releases of a passive tracer from the stack of an incinerator plant located south to the city: one during the early morning, under stable meteorological conditions and weak Northerly winds, and the second in the early afternoon, under weak convection and a light Southerly wind. Also a very peculiar feature of the area was detected by wind profilers, i. e. a low-level valley-exit jet entering the basin through one of the tributary valleys outlet. Tracer concentrations were then measured at selected points in the surroundings. Before and during the releases a modelling chain was run coupling the Weather Research and Forecasting (WRF) model with two different dispersion models: the CALPUFF semi-lagrangian gaussian puff model and the SPRAYWEB particle lagrangian model. After the experiment a verifcation of the modelin chain was pefomed, including a sensitivity analysis to initial/boundary conditions as well as to parameterisations of boundary-layer and turbulent dispersion processes and model setup.

Results from the field campaigns, as well as from simulations performed under different model-chain design and setup, are presented and discussed.