Deviation Range of Annual Dry and Wet Deposition Rates

Abstract

The rate of deposition of airborne pollutants on the ground downwind of a continuously emitting source is evaluated. The annual dry and wet deposition rates deviate from their long-term averages, due to variations of wind direction and velocity, diffusion category, precipitation and of others. Using 14 years of meteorological measurements at the Kernforschungszentrum Karlsruhe (KfK), the computer code ISOLA-IV was applied to calculate the annual deposition rates at the location of the maximum immission downwind of a 100 m high single source, following the German guideline “Allgemeine Berechnungsgrundlage ...”. The deviation range is expressed by the variability, which is defined as the standard deviation being normalized to the average and given in %. The variability of the annual dry and wet deposition rates is up to ± 11 % and ± 27 %, respectively. The related long-term averages (time period of 14 years) are correct with in ± 3 and ± 8 % respectively. For the purpose of extrapolation the wet deposition rate is compared with the total annual precipitation, given for a period of 50 years.