P3.3 Boundary Layer Structure in the Inn Valley during High Air Pollution (innap)

Over the last decades air pollution in the Alpine region has become an intensely debated subject at political and public levels. Clear evidence exists that heavy traffic along the major Alpine transport routes, such as the Brenner route through the Inn Valley (Austria) and over the Brenner Pass, has strongly contributed to the air pollution problem in Alpine valleys (e.g., Beauchamp et al., 2004). The increase of immission of several pollutants, such as nitrogen oxide (NOx) and particulate matter (aerosols) are related to an increase of traffic-induced emission. A traffic scenario for the eastern Inn Valley predicts an increase of the total traffic volume per year of more than 35% between the years 2002 and 2012 (Thudium, 2003). In addition to studies on traffic-flow and emission scenarios, there is a demand for improving the understanding of atmospheric processes which control transport and redistribution of air pollutants over complex terrain. This observational study discusses some of these processes, specifically transport and redistribution by valley and slope winds as well as local dilution through convective and shear-induced turbulent mixing. Subject of our investigation is the wintertime boundary layer of the lower Inn Valley (Austria) during episodes of high air pollution (see Fig. 1). For this purpose, airborne lidar observations have been collected in the winter 2006 within the framework of the research project INNAP∗∗.