Measurements of atmospheric turbulence spectra and cospectra at low heights
in a rural atmospheric surface layer are presented. These show that at low
frequencies the streamwise and transverse spectral densities vary in propo
rtion to the square of the mean velocity. It is also shown that in the iner
tial sub-range the data is well matched by the Kolmogorov law with the Kolm
ogorov constant invariant with height. At intermediate frequencies the data
exhibit spectral power-law regions with exponents that decrease with heigh
t. Spectral models are proposed which closely match these observed behaviou
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