Development and validation of a size-resolved particle dry deposition scheme for application in aerosol transport models

Abstract

A size-resolved particle dry deposition scheme is developed for inclusion inlarge-scale air quality and climate models where the size distribution andfate of atmospheric aerosols is of concern. The "resistance" structure issimilar to what is proposed by Zhang et al. (2001), while a new "surface"deposition velocity (or surface resistance) is derived by simplification of aone-dimensional aerosol transport model (Petroff et al., 2008b, 2009).Compared to Zhang et al.'s model, the present model accounts for the leafsize, shape and area index as well as the height of the vegetation canopy.Consequently, it is more sensitive to the change of land covers, particularlyin the accumulation mode (0.1-1 micron). A drift velocity is included toaccount for the phoretic effects related to temperature and humiditygradients close to liquid and solid water surfaces. An extended comparison ofthis model with experimental evidence is performed over typical land coverssuch as bare ground, grass, coniferous forest, liquid and solid watersurfaces and highlights its adequate prediction. The predictions of thepresent model differ from Zhang et al.'s model in the fine mode, where thelatter tends to over-estimate in a significant way the particle deposition,as measured by various investigators or predicted by the present model. Thepresent development is thought to be useful to modellers of the atmosphericaerosol who need an adequate parameterization of aerosol dry removal to theearth surface, described here by 26 land covers. An open source code isavailable in Fortran90. © Author(s) 2010.