Turbulence spectra and co-spectra from Joint Urban 2003 measurements

There have been only very few investigations devoted to turbulence spectra and co-spectra within and above the urban canopy. We present the results of characteristics of the turbulence spectra and co-spectra obtained from measurements during the Oklahoma City Joint Urban 2003 field experiment. Sonic anemometer data at eight heights taken using Lawrence Livermore National Laboratory 83-m pseudo tower are analyzed. A simple analytical form is used to model the spectra and co-spectra. The form has two free parameters which can be determined from the measurements with a non-linear curve-fitting method. The two parameters can be used to evaluate the peak frequency and wavelength as well as the local isotropy. We focus on the vertical variations of these peak frequencies and wavelengths as well as the local isotropy for urban canopy flow.