Application of a photochemical model in alpine forest sites

Mountain rural sites can be subject to high ozone concentrations (Puxbaum e t al., 1991; Gay, 1991; Sandroni, 1994) that can lead to plant injuries. Ve ry often, unfortunately, such sites do not have a sufficient number of moni toring stations to accurately capture the spatial patterns and temporal evo lution of ozone concentrations. The present study aims at the reproduction of ozone patterns in a forest site an the southern slopes of the Alps. The calculation of ozone concentrations has been carried out for a three days e pisode, by using the CALGRID model. Meteorological fields have been obtaine d by the application of the CALMET model. Emissions have been calculated fo r the main sources categories in the area (biogenic and road transport), wi th a bottom up technique and derived from a regional inventory for minor so urces. Finally, boundary conditions have been derived from a simulation per formed over a larger area (240 x 232 km(2)). The CALGRID model application has provided realistic ground-level concentrations. However, some differenc es have been spotted between estimated and observed concentrations, particu larly at nighttime, when concentrations are more influenced by local effect s. The methodology used and results obtained are presented, the. comparison with measurements and the temporal evolution of ozone vertical profile in different locations of the domain is discussed.