Extending the wind profile much higher than the surface layer

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Extending the wind profile much higher than the
surface layer

• Alfredo Peña, Sven-Erik Gryning,
• Charlotte B. Hasager, and Michael Courtney
• 18 March 2009

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Objectives

• Measurement and modelling of the wind profile in
  and beyond the surface layer
• Modelling of the wind speed profile (mixing
  length)
• Combining wind speed measurements from cups with
  lidar up to 300 m
• Stability of the atmosphere based on sonics close
  to the ground
• Boundary-layer height estimation from ceilometer
  and turbulence measurements

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Theory I
MOST
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Theory II
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Theory III
Mixing-length model
Traditional surface-layer length scale
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Site and measurements
Cups _at_ 10, 40, 60, 80, 100, 116 and 160 m
Sonic vane _at_ 10 m
WindCube lidar _at_ 40, 60, 80, 100, 116, 130, 160,
200, 250 and 300 m
Vaisala CL31 ceilometer
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Stability and mean parameters
Based on 10-min averages, wind speeds gt 2 m/s
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Lidar vs. Cups
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Boundary-layer height

• From ceilometer observations for unstable
  conditions
• From turbulence measurements for neutral and
  stable conditions

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Measurements and traditional wind profiles
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Measurements and wind profile models
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Conclusions

• Using a mixing-length parameterization, the
  derived wind profiles, which account for the
  boundary-layer height, compare better to the
  measurements than the traditional surface-layer
  wind profile
• Measurements of wind speed up to 300 m are
  available from the combination of lidar with cup
  observations that compare well at the overlapping
  heights
• The boundary-layer height is estimated from
  turbulence measurements for neutral and stable
  conditions and ceilometer observations for
  unstable conditions