It has been researched the relationship between deposition velocity and factors which could affect the deposition phenomena and deposition velocity also has been estimated for several land-use types. The typical deposition velocities are complex functions of surface types, atmospheric stabilities, friction velocities, air pollutants and so on. The canopy resistance is major contribution to the model's total resistance for O3. Canopy wetness is also an important factor to calculate deposition velocity. We considered the canopy wetness as canopy water content(CWC) in our Model. But, it is not easy to observe CWC over each land-use types. In this study, we use CWC observed by EMEFS(CANADA Environment Service, 1988) to examine the influence of CWC in estimation of O3 dry deposition velocity(Vd) in summertime. The value of O3 Vd range 0.2～0.7 cms-1 on dry surface and 0.01～0.35 cms-1 on wet surface in daytime.

Land-use types should be included in air pollutant diffusion model because a complex mixture of various land-use patterns with computational grid can make errors in calculation of several parameters. However, the air pollutant diffusion model has generally been treated with a uniform component with land-use type in each mesh because of the complexity of the simulation. This study presents a numerical simulation of the horizontal distribution of O3 dry deposition velocity during summertime in Busan metropolitan city. The calculation of the meteorological field was conducted using the land cover data. Simulation has been performed by the following two scenarios : (1) one with current land cover data, and (2) the other with only land and sea for the surface characteristics. The results from each scenario reveals considerable differences on the meteorological fields and these differences can cause changes in the calculation values of O3 deposition velocity.

The aerodynamic resistance(Ra) to vertical transfer in the surface boundary layer can be formulated in terms of the friction velocity, height of observation, vertical heat flux and surface roughness. Unlike previous studies which focused on the role of Rc, present study perform additional tests using a variety of Ra formulae. Several Ra formulations available in the literature, suitable for unstable conditions, were tested for their influence on the dry deposition velocity. The canopy resistance(Rc) determines the shape of the diurnal pattern, while a small amplitude diurnal cycle in Vd was attributed to the aerodynamic resistance. The aerodynamic resistance is the major contributor to the formation of spikes in nighttime and Ra is relatively important at night because the canopy resistance is smaller. All formulations show similar diurnal cycle and yield good agreement with the observations. Although present Vd formulations are suitable for numerical air quality models, the research must continue for further improvements in resistance parametrizations.

A predictive modal is demonstrated for gas removal rates from the atmosphere by dry deposition. Typical deposition velocities are complex functions of surface types, atmospheric stabilities, friction velocities, air pollutants, and so on. In this paper we simulated the calculation of dry deposition velocities near the earth surfaces, simultaneously we estimated real dry deposition velocities using the previous simulation. The measurement taken over a deciduous forest by Padro et al.(1988) were used to verify this model. In the comparison of the value of deposition velocity between numerical computation and observation, there are partially overestimations and underestimations between them, but we can speak that they are in a good accordance.