Abstract: By using three-dimensional wind speed (u, v, w), air temperature, CO₂, H₂O and other observation data from eddy covariance system in Xiaotang over the northern marginal zone of the Taklimakan Desert, this paper deal with the power spectra and cospectrum of turbulence under different atmospheric stability on typical sunny days in summer. The distribution of turbulent velocity mostly fitted the -2/3 power exponential rate well in Xiaotang, and the vertical high-frequency segment of inertia sub-region more significantly fitted the -2/3 power exponential rate, and then the horizontal direction. The fitting levels of CO₂ and H₂O were lower. The temperature spectrum has a good correlation with the dimensionless frequency in general. The cospectrum slope fitting values of vertical wind speed and radial wind speed u were large and were closer to -1 in most cases, and were more consistent with -4/5 slashes in the near neutral conditions. The cospectrum peak was larger under stable than that at unstable and it was about one magnitude larger. The cospectrum of high frequency segment decreased almost linearly under unstable conditions. The values of the peak wavelengths corresponding to the u spectrum decreased with the increase of stability, and the values of the peak wavelengths corresponding to the v spectrum and the T spectrum does not increased or decreased regularly with the increase of stability. The values of the peak wavelengths of u, v, w, T were about 67-827, 69-2417, 4-54,12-661 m, respectively.

Key words: turbulent spectra, eddy covariance, Taklimakan Desert, oasis-desert transition zone