Abstract
Spectra and variances of velocity components and pressure in stable air were analyzed at the 300 m tower of the BAO.
Spectra in very stable air in light winds usually contain low-frequency fluctuations of large magnitude, and high-frequency fluctuations with considerably less energy, separated by a gap. The wave-length of the gap follows Monin-Obukhov scaling.
The high-frequency portion of the spectra has characteristics of turbulence.
The low-frequency energy is almost certainly due to gravity waves, since there is coherence between vertical velocities and temperatures, and since surface pressure time series resemble time series of velocity components at the higher levels on the tower.
Variances of surface pressure changes appear to be positively correlated with variances of vertical velocity above 100 m, and also to some extent, with horizontal velocity components at all levels. Those results have applications to diffusion estimates from continuous elevated sources, but need confirmation on the basis of measurements elsewhere and additional analyses at BAO.
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Returned to Inst. of Atmospheric Physics, Academia Sinica, Beijing, China.
Retired September 1, 1982.
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Leyi, Z., Panofsky, H.A. Wind fluctuations in stable air at the boulder tower. Boundary-Layer Meteorol 25, 353–362 (1983). https://doi.org/10.1007/BF02041154
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DOI: https://doi.org/10.1007/BF02041154