Abstract : 1B.9
Simulation of the meteorological conditions during a winter smog episode in the Inn Valley with MM5

Irene Schicker, Bernd C. Krueger, Petra Seibert
Institute of Meteorology, University of Natural Resources (BOKU)

In the context of the EU Alpine Space Interreg programme, the project ALPNAP is devoted to scientific methods for air pollution and noise investigation along major Alpine transit routes. Especially large valleys like the Inn Valley

(Tyrol, Austria) are characterised by unfavourable dispersion conditions in winter. Wind velocities are low and the atmosphere is very stable, so that pollutants emitted tend to accumulate near the valley floor and may cause exceedence of air pollution limits. Numerical models are one option to investigate such situations and the impact of emission-side measures. However, in the Alpine topography it is difficult to achieve the needed spatial resolution. G. Zaengl's Alpine version of MM5 has opened new possibilities for such simulations, and we are applying it to simulate a one-week episode during February 2004 with a grid distance of 0.67 km in the innermost nest.

It is characterised by a high-pressure system centred over the Western Mediterranean and extending over the whole Alps. The daily temperature amplitude is 10-15 degree, and the wind speed in Innsbruck is 1-2 m/s. Results will be compared with wind and temperature observations along the valley and on the mountain stations, and the Innsbruck radiosonde ascents. We aim at adding a simulation of atmospheric chemistry and dispersion with the CAMx chemistry model.