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.