ESTIMATION OF DRY DEPOSITION IN THE BORNHOVED LAKE DISTRICT WITH A RESISTANCE MODEL

Dry deposition of gaseous air pollutants is an important input pathway of acidifying and eutrophying compounds to various ecosystems. Howeve r, it cannot be measured on a routine basis under many circumstances. For monitoring purposes, inferential methods based on measured air con centrations and electrical resistance analogy models have been develop ed. In this paper, the application of such a model system to the Bornh oved Lakes research area, model tests, modelling results and a compari son, taking SO2 deposition as an example, with an independent method t o estimate dry deposition to forest canopies (net throughfall) are pre sented. The turbulent and quasi-laminar boundary layer resistances are modelled according to micrometeorological theory and by using empiric al similarity functions, respectively. Surface resistances are estimat ed with a modular partial resistance model system after Wesely (Atmosp heric Environment 23 (1989) 1293-1304). The temporal behavior is shown to be realistic. However, the computed SO2 deposition rates to a beec h canopy are much lower than the SOx dry deposition as determined by n et throughfall. Possible reasons for this discrepancy due to model wea knesses concerning the effects of, e.g., surface wetness and complex t errain on dry deposition are discussed, as well as the advantages of t he resistance analogue model.