Record Display for the EPA National Library Catalog
RECORD NUMBER: 183 OF 197
|OLS Field Name||OLS Field Data|
|Main Title||Surface inhomogeneity effects on convective diffusion /|
|Author||Briggs, Gary A.|
|CORP Author||Environmental Sciences Research Lab., Research Triangle Park, NC. Meteorology and Assessment Div.|
|Publisher||United States Environmental Protection Agency, Office of Research and Development, Atmospheric Sciences Research Laboratory,|
|Additional Subjects||Atmospheric diffusion ; Urban areas ; Heat flux ; Wind velocity ; Atmospheric models ; Mathematical models ; Reprints ; Convection(Atmospheric) ; Atmospheric turbulence ; Saint Louis(Missouri)|
|Collation||21 pages ; 28 cm|
It is suggested that convective scaling, with appropriate extensions, provides the most useful framework for estimating the effects of urban-scale surface inhomogeneities on diffusion in convective conditions. Strong contrasts in surface heat flux exist between cropland, forests, urban areas, and water or marshland surfaces. It is argued that a typical fetch for convective turbulence to readjust to changed heat (or buoyancy) input from the surface below is 2(U/w*)z(j), where U is the mean wind speed in the mixing layer, w* is the convective scaling velocity, and z(j) is the mixing depth. The ratio w*/U is the best index of diffusion rates in moderately to very unstable conditions. General urban effects on heat flux, z(j), and U are discussed separately, then their combined effects on w*/U are estimated. Finally, some examples of heat flux inhomogeneities causing stationary convective features are presented.
"Reprint article published in Boundary-Layer Meteorology, vol. 45(1988), pp. 117-135." Caption title. "Journal article." Microfiche.