Modelling atmospheric dry deposition in urban areas using an urban canopy approach
Atmospheric dry deposition is typically modelled using an average roughness length, which depends on land use. This classical roughness-length approach cannot account for the spatial variability of dry deposition in complex settings such as urban areas. Urban canopy models have been developed...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-03-01
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| Series: | Geoscientific Model Development |
| Online Access: | http://www.geosci-model-dev.net/8/893/2015/gmd-8-893-2015.pdf |
| Summary: | Atmospheric dry deposition is typically modelled using an average roughness
length, which depends on land use. This classical roughness-length approach
cannot account for the spatial variability of dry deposition in complex
settings such as urban areas. Urban canopy models have been developed to
parametrise momentum and heat transfer. We extend this approach here to mass
transfer, and a new dry deposition model based on the urban canyon concept is
presented. It uses a local mixing-length parametrisation of turbulence
within the canopy, and a description of the urban canopy via key parameters
to provide spatially distributed dry deposition fluxes. Three different flow
regimes are distinguished in the urban canyon depending on the
height-to-width ratio of built areas: isolated roughness flow, wake
interference flow and skimming flow. Differences between the classical
roughness-length model and the model developed here are
investigated. Sensitivity to key parameters are discussed. This approach
provides spatially distributed dry deposition fluxes that depend on surfaces
(streets, walls, roofs) and flow regimes (recirculation and ventilation)
within the urban area. |
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| ISSN: | 1991-959X 1991-9603 |