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Boundary-Layer Meteorology

, Volume 124, Issue 3, pp 449–463 | Cite as

Turbulence spectra in the near-neutral surface layer over the Loess Plateau in China

  • Wei LiEmail author
  • Tetsuya Hiyama
  • Nakako Kobayashi
Original Paper

Abstract

We present the power spectra of wind velocity and the cospectra of momentum and heat fluxes observed for different wind directions over flat terrain and a large valley on the Loess Plateau. The power spectra of longitudinal (u) and lateral (v) wind speeds satisfy the −5/3 power law in the inertial subrange, but do not vary as observed in previous studies within the low frequency range. The u spectrum measured at 32 m height for flow from the valley shows a power deficit at intermediate frequencies, while the v spectrum at 32 m downwind of the valley reaches another peak in the low frequency range at the same frequency as the u spectrum. The corresponding peak wavelength is consistent with the observed length scale of the convective outer layer at the site. The v spectrum for flat terrain shows a spectral gap at mid frequencies while obeying inner layer scaling in its inertial subrange, suggesting two sources of turbulence in the surface layer. All the spectra and cospectra from the valley direction show a height dependency over the three levels.

Keywords

Cospectra Loess Plateau Power spectra Spectral gap Topography 

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Copyright information

© Springer Science+Business Media, B.V. 2007

Authors and Affiliations

  1. 1.Graduate School of Environmental StudiesNagoya UniversityNagoyaJapan
  2. 2.Hydrospheric Atmospheric Research CenterNagoya UniversityNagoyaJapan

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