Assessment of pollutant fluxes across the frontiers of the Federal Republic of Germany on the basis of aircraft measurements

Abstract Forty operational measurements by aircraft are described, which were performed during 1985–1987. The purpose was to obtain an overall picture of transboundary transports of SO 2 , NO x sulfate, nitrate and O 3 between the F.R.G. and its neighbours. Transboundary fluxes were calculated by means of measurement results with respect to the concentrations of the considered pollutants, depth of the planetary boundary layer, wind speed and wind direction. The largest SO 2 fluxes have been observed across the eastern border of the F.R.G., during periods characterized by easterly winds (300–2500 ton SO 2 h −1 across a 500–600 km border section). The major fraction of this SO 2 appeared to have originated from the easterly neighbours of the F.R.G. and to a lesser extent also from countries further eastward. During easterly winds it has been observed that SO 2 , which originated from countries east of the F.R.G., contributed considerably to SO 2 fluxes across the western border to countries west of the F.R.G. The results of the measurement flights as presented have provided valuable indications about transboundary transports of pollutants despite considerable uncertainties in the fluxes due to inaccuracies in the concentration profiles, wind data and depth of the planetary boundary layer.