Urban boundary layer

Bornstein et al.. Simulation of Urban Earner Effects on Polluted Urban Boundary Layers Using the Three-Dimensional URBMET TVM Model with Urban Topography, Air Pollution Proceedings, 1993. 

A very comprehensive study of urban boundary layer characteristics was made by Theurer, 1992 [608] to summarize what is know about these parameters and to correlate them with building dimensions. Theurer used two parameters to describe the distribution of roughness elements ... 

The parameterisation has been tested on the city of Basel (Switzerland), Mexico City (Mexico), Copenhagen (Denmark), and verified versus the BUBBLE experiment (Basel Urban Boundary Layer Experiment Rotach et al., 2005 [549]). The verification results (Figure 9.11) show that the urban parameterization scheme is able to catch most of the typical processes induced by an urban surface Inside the canopy layer, the wind speed, the friction velocity and the atmospheric stability are reduced. In the other hand, even if the main effects of the urban canopy are reproduced, the comparison with the measurement seems indicates that some physical processes are still missing in the parameterization. In most of the cases, the model still overestimates the wind speed inside the canopy layer and it can have difficulties to simulate the maximum of the friction velocity which appears above the building roofs. 

Belcher, S.E., and Coceal, O. (2002) Scaling the urban boundary layer. In Ro-tach M., Fisher B., Piringer M. (Eds.), COST Action 715 Workshop on Urban Boundary Layer Parameterisations (Zurich, 24-25 May 2001). Office for Official Publications of the European Communities, EUR 20355, 7-16. 

Bornstein, R.D. (1987) Mean diurnal circulation and thermodynamic evolution of urban boundary layers, Modelling the urban boundary layer, published by American Meteorological Society, Boston, MA, 53-94. 

Hamdi, M., and Schayes, G. (2005) Validation of the Martilli s Urban Boundary Layer Scheme with measurements from two mid-latitude European cities, Atmos. Chem. Phys. Discuss. 5, 4257 289. 

Sorbjan, Z and Uliasz, M. (1982) Some numerical urban boundary-layer studies, Boundary-Layer Meteorology 22,481-502. 

Henninger, S. and W. Kuttler (2004) Mobile measurements of carbon dioxide in the urban boundary layer of Essen, Germany. In 5 Urban Environment Symposium, Vancouver, Canada, American Meteorological Society, J 12.3. (5 pp.)... 

Measurements of OH and HO2 have been made in the upper troposphere using aircrafts, and in the marine, forest and urban boundary layers. From the point of validation of HOx reaction mechanism, it implies verification for more complex systems with more variety of chemical species in this order. 

This report deals primarily with the origins and effects of ozone and other photochemical oxidants. It is limited, more or less, to the problem of urban pollution and to such closely related topics as natural background in the earth s boundary layer. No consideration is given to the stratospheric ozone layer and the effects produced by supersonic transport (sst) emission or halocarbons. 

Figure 3.25 shows the results of one set of calculations of the effects of aerosol particles whose properties were judged to be characteristic of continental or urban situations, respectively, on the transmission of UV and visible radiation to the earth s surface (Erlick and Frederick, 1998). The ratio of the transmission with particles to that without is plotted in two wavelength regions, one in the UV and one in the visible. Two different relative humidity scenarios are shown. The average summer relative humidity was 70% RH in the boundary layer and 20% RH in the free troposphere. The high relative humidity case assumes 90% RH in the boundary layer and 30% in the free troposphere. (The RH in the stratosphere was taken to be 0% in both cases see Chapter 12.)... 

Al-Wali, K. I., and P. J. Samson, Preliminary Sensitivity Analysis of Urban Airshed Model Simulations to Temporal and Spatial Availability of Boundary Layer Wind Measurements, Atmos. Environ., 30, 2027-2042 (1996). 

The observed sulfate reduction rates in freshwater sediments cannot be explained by diffusion of sulfate from the lake water into the sediment, because much steeper sulfate concentration gradients should then be observed. Assuming diffusive supply alone, Urban (28) calculated that the change of sulfate concentration with depth should take place within 1 mm instead of several centimeters, which are usually measured. This assumption, however, also means that the sulfate recycling process and the sulfate reduction rate should not be limited by the vertical transport of sulfide to (frequently solid) oxidants or to the oxic boundary layer. 

Night-time emission rates in rural and urban areas are listed in Table I together with initial concentrations and land deposition velocities. The initial concentrations were chosen to reflect unpolluted air arriving at the West Coast of England. Methane is assumed to be present in the atmospheric boundary layer at a constant concentration of 1.6 ppm. Water vapour is also assumed to be invariant in rural and urban air at a concentration of 104 ppm. This corresponds to ca. 60% relative humidity at 288 K. The initial concentration and emission over land of DMS have been taken to be zero as have all other species in the chemical scheme which are not listed in Table I. Emissions over land of NO, SO hydrocarbons, CO and H are subject to diurnal variation and this has been treated as before (13.141. Rural emission rates are assumed to prevail throughout the traversal of Scandinavia. All species are assumed to be hilly mixed within an atmospheric boundary layer of constant depth, taken to be... 

Half-angle for Horizontal Dispersion Half-angle for Vertical Dispersion Boundary-layer Depth Initial Cross-section of Plume Distance from West Coast to Urban Area Length of Urban Area Width of Urban Area... 

Farrar, N.J., Hamer, T., et al. (2004a) Field deployment of thin film passive air samplers for persistent organic pollutants a study in the urban atmospheric boundary layer. Environmental Science and Technology, 39(1) 42-A8. 

It is known that the boundary layer in the urban areas has a complex structure due to multiple contributions of different parameters, including variability in roughness and fluxes, etc. All these effects can be included to some extend into models. For research purposes, the DMI-HIRLAM-UOl/IOl models (resolution of 1.4 km) with domains shown in Fig. 16.2 are employed for high resolution urbanized modelling (example is shown in Fig. 16.6b). The land-use classification is based on CORINE dataset (http //etc-lusi.eionet.europa.eu/CLC2000) and climate generation files. 

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