The long-range transport of ammonia and ammonium in the Northern Hemisphere

The results of model evaluation of the long-range ammonia and ammonium airborne transport in the Northern Hemisphere are presented. For emitter-receiver relationship calculations, the current Eulerian model of the Meteorological Synthesizing Centre-East (MSC-E) with spatial resolution 150 km x 150 km is used. The model considers the vertical pollution distribution in the whole troposphere and chemical transformation of reduced nitrogen. The calculation area covers the Northern Hemisphere to the North of 20 degrees. The actual meteorological parameters with a 6 h time step are obtained from weather prediction model, with emission data and geographical information being used as input data. Emission data are taken from official sources or made by experts in case of absence of official information. Results of model calculations made for the Northern Hemisphere show that the distance of ammonia transport is less than that of oxidised sulphur and nitrogen. There are three almost self-polluted-Europe + Central Asia + Middle East, southwestern Asia and North America. Transport from America to Eurasia is negligible. There is a significant redistribution of reduced nitrogen within the three above-mentioned regions. (C) 1998 Elsevier Science Ltd. All rights reserved.