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ESTIMATING GASEOUS EXCHANGES BETWEEN THE ATMOSPHERE AND PLANTS USING A COUPLED BIOCHEMICAL DRY DEPOSITION MODEL
Citation:
Wu, Y., B. Brashers, P L. Finkelstein, AND J E. Pleim. ESTIMATING GASEOUS EXCHANGES BETWEEN THE ATMOSPHERE AND PLANTS USING A COUPLED BIOCHEMICAL DRY DEPOSITION MODEL. Presented at American Geophysical Union Fall Meeting, San Francisco, CA, December 13-17, 1999.
Impact/Purpose:
This task has the following objectives:
Improve modelers' ability to focus on scientific and policy issues in modeling studies by providing software that supports composing, applying, and evaluating complex systems of models.
Improve the understanding of the interaction of the atmosphere and the underlying surface, especially the flux of mass in both directions, and EPA's ability to simulate that interaction.
Contribute to multimedia studies and assessments by applying state-of-the-art atmospheric models, estimating atmospheric contributions to multimedia issues and the sources of those contributions, and evaluating the models' strengths and weaknesses.
Description:
To study gaseous exchanges between the soil, biosphere and atmosphere, a biochemical model was coupled with the latest version of Meyers Multi-Layer Deposition Model. The biochemical model describes photosynthesis and respiration and their coupling with stomatal resistance for both sunlit and shaded leaves. Various aspects of the photosynthetic process in both C3 and C4 plants are considered in the model, such as the efficiency of the photosynthetic enzyme system, the amount of photosynthetically active radiation and the capacity of the leaf to export or utilize the products of photosynthesis. In addition, a normalized soil water stress factor was applied to the potential photosynthesis to account for plant response to both drought and waterlogging stresses. The model can account for the direct, indirect and tightly coupled effects of environmental factors on stomatal regulation of gaseous exchanges between plants and their environment. The coupled biochemical dry deposition model was tested against eddy correlation data from six field experiments. It is shown that the coupled model is able to estimate water vapor, carbon dioxide and ozone fluxes correctly, and the model results compare well with measurements made in the field. The model is for use in the nationwide dry deposition network?CASTNet, and will assist in detecting total pollutant loadings to major ecosystems.