Densely populated areas are situated in the Austrian Rhine Valley. Emissions from industries and traffic impair the
air quality of the region. A main impact comes from high concentrations of ozone.
Air pollution is generally very sensitive to Foehn. The penetration of Foehn to the ground can bring a relief to some
valley segments. In other cases, ozone-rich air is advected with the Foehn flow. The interaction of the low and mid-
tropospheric Foehn air with the atmosphere within the Rhine valley is spatially and temporarily extremely variable.
These unstationary aspects of Foehn are one of the objectives of MAP. In the project ROM, ozone is used as a
tracer to detect areas, where the boundary layer has been eroded by the Foehn flow, valley segments with mixed air
and areas with stagnant air (e.g. cold air pool under an inversion).
The vertical structure and temporal evolution of the boundary layer and its constituents (esp. ozone) will be
documented with vertical profile measurements with an acoustic radar, a tethered balloon system and a sonde fixed
at a cable car. Based on these data, schematic horizontal and vertical distributions of the air masses of different
origin and composition will be deduced for several time-steps throughout the Foehn events. These experimental
concepts will be examined afterwards with numerical model simulations using the mesoscale model MM5 with a
horizontal gridsize of 1-2 km.