A revised parameterization for gaseous dry deposition in air-quality models

[摘要] A parameterization scheme for calculating gaseous dry deposition velocities inair-quality models is revised based on recent study results on non-stomatal uptake ofO₃ and SO₂ over 5 different vegetation types. Non-stomatal resistance, which includes in-canopyaerodynamic, soil and cuticle resistances, for SO₂ and O₃ is parameterized as a function offriction velocity, relative humidity, leaf area index, and canopy wetness.Non-stomatal resistance for other chemical species is scaled to those ofSO₂ and O₃ based on their chemical and physical characteristics. Stomatal resistance is calculated using a two-big-leaf stomatal resistancesub-model for all gaseous species of interest. The improvements in the present model compared to itsearlier version include a newly developed non-stomatal resistance formulation, a realistictreatment of cuticle and ground resistance in winter, and the handling of seasonally-dependentinput parameters. Model evaluation shows that the revised parameterization can provide morerealistic deposition velocities for both O₃ and SO₂, especially for wet canopies. Example modeloutput shows that the parameterization provides reasonable estimates of dry deposition velocitiesfor different gaseous species, land types and diurnal and seasonal variations. Maximumdeposition velocities from model output are close to reported measurement values for differentland types. The current parameterization can be easily adopted into different air-quality modelsthat require inclusion of dry deposition processes.

[学科分类] 大气科学