A multi-layer model vs single-layer models and observed O3 dry deposition velocities

A multi-layer dry deposition model is compared with three single-layer models and with O3 measurements available for a fully leafed and leafless deciduous forest, a cotton field and a vineyard. When compared with the multi-layer model, the dry deposition velocities computed with the single-layer models agree better with the observations over the forest but not as well over the remaining surface types. Sensitivity tests with the multi-layer model indicate that these uncertainties may be caused primarily by input parameters such as stomatal, cuticle and soil resistances and the radiation formulation. These uncertainties are likely to persist for some time until we can assign more definite values to the resistances.