WSEAS Transactions on Environment and Development
Print ISSN: 1790-5079, E-ISSN: 2224-3496
Volume 11, 2015
Spectral Characteristics of the Wind Components in the Surface Atmospheric Boundary Layer
Authors: ,
Abstract: The objective of this work is the study of the spectral characteristics of the wind components in the surface Atmospheric Boundary Layer (ABL). The analyzed data are based on an experimental campaign measurements which has been conducted in the framework of the European project ECATS, at the Athens International Airport (AIA), Greece, from 13th to 25th of September 2007, with the use of remote sensing and in situ instrumentation. Among other instrumentation, a 10 m high meteorological mast was installed, equipped with a sonic anemometer and a fast hygrometer at 10 m height, with high frequency (20 Hz) sampling, for the three-dimensional wind components (u, v and w) and virtual temperature (T) measurements, as well as for water vapor (q) measurements. These high frequency measurements yield estimates of the vertical transport of the momentum (u’w’ and v’w’), the heat (w’T’) and the humidity (w’q’) fluxes through the eddy correlation method, for 10-min time intervals. In order to quantify the background air flow, additional information related to the synoptic conditions as well as radiosonde data from a nearby station was also used. Spectra of the wind components (u, v and w) were also calculated and analyzed. Results showed that the slope values of the spectra at the inertial sub-range reveal certain deviations from the expected theoretical ones, but the mean values eliminate these deviations between theory and observations. Also, the atmospheric stability and the mean wind speed influence the slope values of the spectra. According to the analysis an increase of the wind speed or the friction velocity lead to a decrease of the spectra slope values while the evolution of the atmospheric stability from unstable to stable conditions increase the spectra slope values which generally become steeper, meaning that the turbulence in the surface ABL dissipates faster than expected.
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Pages: 73-79
WSEAS Transactions on Environment and Development, ISSN / E-ISSN: 1790-5079 / 2224-3496, Volume 11, 2015, Art. #8