High resolution maps of nitrogen dioxide for the Province of Styria, Austria

Abstract

Knowledge about the spatial distribution of NO2 concentrations is beneficial for setting up air quality measurement plans, assessing exposure, or in licensing procedures, where background concentration levels are required. Styria (16.400 km², 1.2 million population) is the second largest province in Austria. In order to take topographical effects on the pollutant dispersion into account, wind field libraries have been computed using the prognostic non-hydrostatic model GRAMM. Local observations of wind speed, direction and estimated stability classes have been used as meteorological input. Subsequently, quasi steady state wind fields have been computed and stored for later use in dispersion modelling utilising the Lagrangian particle model GRAL. In order to capture strong NO2 concentration gradients (e.g., near roads), 10 m horizontal grid spacing was used in dispersion calculations. Building effects on dispersion have been taken into account by applying a simple mass-conservative diagnostic flow field model implemented in GRAL.