A multilayer biochemical dry deposition model 1. Model formulation

Abstract

A multilayer biochemical dry deposition model has been developed based on the NOAA Multilayer Model (MLM; Meyers et al. [1998]) to study gaseous exchanges between the soil, plants, and the atmosphere. Most of the parameterizations and submodels have been updated or replaced. The numerical integration was improved, and an aerodynamic resistance based on Monin-Obukhov theory was added. An appropriate parameterization for the leaf boundary layer resistance was chosen. A biochemical stomatal resistance model was chosen based on comparisons of four different existing stomatal resistance schemes. It describes photosynthesis and respiration and their coupling with stomatal resistance for sunlit and shaded leaves separately. Various aspects of the photosynthetic process in both C3 and C4 plants are considered in the model. To drive the photosynthesis model, the canopy radiation scheme has been updated. Leaf area index measurements are adjusted to account for stem area index. A normalized soil water stress factor was applied to potential photosynthesis to account for plant response to both drought and water-logging stresses. A new cuticle resistance model was derived based on membrane passive transport theory and Fick's first law. It accounts for the effects of diffusivity and solubility of specific gases in the cuticle membrane, as well as the thickness of the cuticle membrane. The model is designed for use in the nationwide dry deposition networks, for example, the Clean Air Status And Trends Network (CASTNet , and mesoscale models, for example, the Community Multiscale Air Quality model (CMAQ) and even the Weather Research and Forecasting model (WRF).