STRATIFICATION EFFECT ON THE ROUGHNESS LENGTH

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STRATIFICATION EFFECT ON THE ROUGHNESS LENGTH

• S. S. Zilitinkevich1,2,3, I. Mammarella1,2,
• A. Baklanov4, and S. M. Joffre2
• 1. Atmospheric Sciences, University of
  Helsinki, Finland
• 2. Finnish Meteorological Institute,
  Helsinki, Finland
• 3. Nansen Environmental and Remote Sensing
  Centre /
• Bjerknes Centre for Climate Research,
  Bergen, Norway
• 4. Danish Meteorological Institute, Copenhagen,
  Denmark

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References

• S. S. Zilitinkevich, I. Mammarella, A. A.
  Baklanov, and S. M. Joffre, 2007 The roughness
  length in environmental fluid mechanics the
  classical concept and the effect of
  stratification. Submitted to Boundary-Layer
  Meteorology.

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Content
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Surface layer and roughness length
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Parameters controlling z 0u
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Stability Dependence of Roughness Length
For urban and vegetation canopies with
roughness-element heights (20-50 m) comparable
with the Monin-Obukhov turbulent length scale, L,
the surface resistance and roughness length
depend on stratification
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Background physics and effect of stratification
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Recommended formulation
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(No Transcript)
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Stable stratification
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Stable stratification
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Stable stratification
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Unstable stratification
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Unstable stratification
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Unstable stratification
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STABILITY DEPENDENCE OF THE ROUGHNESS LENGTHin
the meteorological interval -10 lt h0/L lt10
after new theory and experimental data Solid
line z0u/z0 versus h0/L Dashed
line traditional formulation z0u z0
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Conclusions (roughness length)

• Traditional concept roughness length fully
  characterised by geometric features of the
  surface
• New theory and data essential dependence on
  hydrostatic stability
• especially strong in stable stratification
• Applications to urban and terrestrial-ecosystem
  meteorology
• Practically sound urban air pollution episodes
  in very stable stratification

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NEUTRAL and STABLE ABL HEIGHT

• Sergej Zilitinkevich 1,2,3,
• Igor Esau3 and Alexander Baklanov4
• 1 Division of Atmospheric Sciences, University of
  Helsinki, Finland
•  
• 2 Finnish Meteorological Institute, Helsinki,
  Finland
• 3 Nansen Environmental and Remote Sensing Centre
  / Bjerknes Centre for Climate Research, Bergen,
  Norway
• 4 Danish Meteorological Institute, Copenhagen,
  Denmark

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References

• Zilitinkevich, S., Baklanov, A., Rost, J.,
  Smedman, A.-S., Lykosov, V., and Calanca, P.,
  2002 Diagnostic and prognostic equations for the
  depth of the stably stratified Ekman boundary
  layer. Quart, J. Roy. Met. Soc., 128, 25-46.
• Zilitinkevich, S.S., and Baklanov, A., 2002
  Calculation of the height of stable boundary
  layers in practical applications. Boundary-Layer
  Meteorol. 105, 389-409.
• Zilitinkevich S. S., and Esau, I. N., 2002 On
  integral measures of the neutral, barotropic
  planetary boundary layers. Boundary-Layer
  Meteorol. 104, 371-379.
• Zilitinkevich S. S. and Esau I. N., 2003 The
  effect of baroclinicity on the depth of neutral
  and stable planetary boundary layers. Quart, J.
  Roy. Met. Soc. 129, 3339-3356.
• Zilitinkevich, S., Esau, I. and Baklanov, A.,
  2007 Further comments on the equilibrium height
  of neutral and stable planetary boundary layers.
  Quart. J. Roy. Met. Soc., 133, 265-271.

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Factors controlling PBL height
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Scaling analysis
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Dominant role of the smallest scale
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How to verify h-equations?
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Stage I Truly neutral ABL
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Stage I Transition TN?CN ABL
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Stage I Transition TN?NS ABL
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Stage II General case
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Conclusions (SBL height)