Recent Improvements to the Meyers Multi-layer Dry Deposition Model

Recent work to improve the Meyers Multi-layer Dry Deposition Model is presented. New biochemical models for stomatal and cuticular conductance have been added, as well as more sophisticated parameterizations for the aerodynamic and (leaf) boundary layer resistances. Monin-Obukhov similarity theory is used to parameterize the aerodynamic resistance, and several boundary layer resistance schemes are explored including recent work by Massman. The radiation model has been revamped to give results that are independent of the number of layers in the canopy, and an ellipsoidal leaf-angle distribution parameterization was added. Sun-lit and shaded leaves are treated separately, where PAR drives a photosynthesis model that is also limited by the efficiency of the photosynthetic enzyme system, the amount of hotosynthetically active radiation and the capacity of the leaf to export or utilize the products of photosynthesis. model results are compared with data from 6 extensive field studies over corn, soybeans and pasture as well as both mixed and deciduous forests, where fluxes of CO2, H2O, O3 and SO2 were measured using eddy correlation. The model is also compared with the previous version of the Meyers Multi-layer Model, as well as the Wesely (RADM) model.