A revised parameterization for gaseous dry deposition in air-quality models L. Zhang, J. R. Brook, and R. Vet Meteorological Service of Canada, 4905 Dufferin Street, Toronto, Ontario, M3H 5T4, Canada
Abstract. A parameterization scheme for calculating gaseous dry deposition velocities in
air-quality models is revised based on recent study results on non-stomatal uptake of
O3 and SO2 over 5 different vegetation types. Non-stomatal resistance, which includes in-canopy
aerodynamic, soil and cuticle resistances, for SO2 and O3 is parameterized as a function of
friction velocity, relative humidity, leaf area index, and canopy wetness.
Non-stomatal resistance for other chemical species is scaled to those of
SO2 and O3 based on their chemical and physical characteristics. Stomatal resistance is calculated using a two-big-leaf stomatal resistance
sub-model for all gaseous species of interest. The improvements in the present model compared to its
earlier version include a newly developed non-stomatal resistance formulation, a realistic
treatment of cuticle and ground resistance in winter, and the handling of seasonally-dependent
input parameters. Model evaluation shows that the revised parameterization can provide more
realistic deposition velocities for both O3 and SO2, especially for wet canopies. Example model
output shows that the parameterization provides reasonable estimates of dry deposition velocities
for different gaseous species, land types and diurnal and seasonal variations. Maximum
deposition velocities from model output are close to reported measurement values for different
land types. The current parameterization can be easily adopted into different air-quality models
that require inclusion of dry deposition processes.
Citation: Zhang, L., Brook, J. R., and Vet, R.: A revised parameterization for gaseous dry deposition in air-quality models, Atmos. Chem. Phys., 3, 2067-2082, doi:10.5194/acp-3-2067-2003, 2003.