Assessing the meteorological conditions of a deep Italian Alpine valley system by means of a measuring campaign and simulations with two models during a summer smog episode

The typical features of a summer smog episode in the highly complex terrain of the Province of Bolzano (Northern Italy) were investigated by numerical modelling with two non-hydrostatic models, ground-based monitoring station s, and vertical profiling with two sodars and an ultra-light aircraft. High ozone concentrations are most likely to appear in situations where the loc al circulation in the valleys is decoupled from the synoptic flow above dur ing anticyclonic weather regimes. Both models (MM5 and TVM) produced simila r results and were able to simulate the local winds in the valleys. A compa rison of the measured data to the model simulation results made an evaluati on of the performance of the two models in such complex terrain possible. B oth models proved to be suitable for the simulation of the meteorological c onditions during such summer smog episodes in complex terrain. (C) 2001 Els evier Science Ltd. All rights reserved.