Evaluation of the operational Swiss weather forecast model for air quality applications in the Po Basin south of the Alps

High primary and secondary pollutant concentrations prevail in the Po Basin in southern Italy. This is due to the high emissions and the meteorological conditions conducive to photo-oxidant formation. The Po Basin is the major source of air pollution also for the adjacent Alpine area. Due to its position close to the southern Alpine main range, complex boundary layer and flow conditions predominate. Since long-term studies of pollutant transport and transformation require the use of operationally available meteorological model information, we investigate the performance of the Swiss weather forecast model (horizontal resolution 14 km) in simulating boundary layer structure and horizontal transport in this area. Emphasis is put on boundary layer height comparisons and on the comparison of vertical profiles of horizontal wind components. For that purpose, we make use of operational soundings as well as of wind profiler measurements. Furthermore, we compare measured concentrations of less reactive air pollutants (benzene, carbon monoxide, total reactive nitrogen) with results of Lagrangian particle model simulations based on swiss model fields and improved emission estimates.