Evaluation of a Coupled Land-Surface and Dry Deposition Model through Comparisonto Field Measurements of Surface Heat, Moisture, and Ozone Fluxes

摘要

The Fifth Generation Mesoscale Model has been modified to include an improvedland-surface scheme with explicit treatment of soil moisture and evapotranspiration. A key aspect of this work is an indirect soil moisture nudging scheme which adjusts soil moisture according to model errors in surface level temperature and humidity. Since stomatal resistance is an important component of both evapotranspiration and dry deposition, a chemical dry deposition model is coupled to the land surface scheme through the use of several common elements. Both aerodynamic and bulk stomatal resistance computed in the evapotranspiration model are used to compute dry deposition of gaseous species. This technique has the advantage over many other dry deposition models of being able to respond to changing soil moisture conditions. Also, the soil moisture adjustment scheme should result in more realistic stomatal conductances and dry deposition veolocities. The current study focuses on comparison of model simulations to field measurements made in a soybean field in southern Kentucky during the summer of 1995.