A STATISTICAL APPROACH TO ESTIMATE SPATIAL DISTRIBUTIONS OF WET DEPOSITION IN GERMANY

摘要

The correct spatial interpolation from a few available point measurements of wet deposition - which contributes a major part to total deposition - is very important for the determination of a possible exceeding of critical loads: A wide spatial variability is a property of both deposition and critical loads. For this purpose, the meteorological variables having relevant influence on wet deposition and being available from routine measurements were used as input data for a statistical model for the estimation of wet deposition. Those variables are precipitation amount, preceding dry period, wind direction and season. The results obtained from the developed model were validated using measurements from routine monitoring stations in Germany for daily wet deposition rates of the major anions and cations. After description of model development and verification, the application of the model is presented exemplarily for sulfate, chloride and nitrate. Therefore daily precipitation data from a few representative monitoring stations and additional information about wind direction from meteorological maps were used as model input. As a result, reliable point estimates for wet deposition were available in addition to the measured data, thus allowing spatial interpolation with higher accuracy. The resulting wet deposition maps reveal that the critical loads for the investigated substances are already exceeded in some areas of Germany, particularly when the additional input from dry and occult (fog and cloud) deposition is taken into account. Using all available daily precipitation data in an annual routine, deposition maps could be available with high spatial resolution (<10 km).