Boundary-Layer Meteorology

, Volume 14, Issue 3, pp 323–330

Aerodynamic roughness as a function of wind direction over asymmetric surface elements

  • B. S. Jackson
  • J. J. Carroll


Wind speed and temperature profiles to a height of 8 m were recorded for 30-, 60-, and 90-min averaging times over a striated snow surface at the geographic South Pole during the austral winter of 1975. A gradient Richardson number was calculated for each averaging time to determine conditions of neutral stability under which the logarithmic wind law would hold. A log-linear regression technique was used to determine values of aerodynamic roughness height (Z0) for those profile averages recorded in conditions of neutral stability. A plot of Z0 as a function of average wind direction revealed a variation in Z0 of almost three orders of magnitude, from 0.01 to 7 cm, over 120 deg of wind direction. A simple model is presented to justify the fact that aerodynamic roughness is a function of wind direction and erosion history.


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Copyright information

© D. Reidel Publishing Company 1978

Authors and Affiliations

  • B. S. Jackson
    • 1
  • J. J. Carroll
    • 1
  1. 1.Dept. of Land, Air and Water Resources, Atmospheric Science SectionUniversity of CaliforniaDavisUSA

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