ISSN:
1573-1472
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Abstract A large number of hourly averages of wind profiles from a 100-m mast at the urban-rural border of Uppsala, central Sweden, are analysed. In all, more than 4000 hr of measurements are available from the period treated (1974–1976). About 1/3 of these are excluded in a series of checks to assure a high degree of accuracy in the data used. The profiles are analysed concerning the applicability of three different profile formulas: the power-law, the logarithmic law and the so-called log-linear relation. All three are studied in relation to their dependence on atmospheric stability and fetch conditions, i.e., the profiles are analysed statistically in terms of mean quantities for a number of stability and wind direction classes. Due to the location of the measuring site, more than one internal boundary layer (IBL) — one of which is urban — are involved for a majority of wind directions. Hence, all analyses are carried out separately for two different layers, one lower and one upper. Provided that the different IBL's are treated separately, the analysis clearly shows that the power-law provides a very useful profile description under widely varying conditions, but also that the logarithmic law mostly gives a good formal fit, even under non-neutral conditions; then however, the apparent roughness length z 0 varies considerably from the ordinary neutral value. The log-linear relation does not seem to apply unless the constant α in the equation is allowed to vary significantly over the stability range considered.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00120987
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