We are conducting  a pilot study to evaluate methods for the estimations of aerodynamic roughness parameters (i.e., roughness length (z0), zero plane displacement height (d)) from single-level eddy covariance measurements. Results will guide development for future AmeriFlux and FLUXNET datasets.  Thanks to the flux community, most required variables are available through the AmeriFlux database (e.g., wind speed (WS), friction velocity (USTAR), wind direction (WD), Monin-Obukhov length (MO_LENGTH)).

Now we are calling for flux site data for critical but missing variables.

  • W_SIGMA Standard deviation of vertical wind velocity (m/s) at eddy covariance level (after coordinate rotation)
  • WS_# Additional level(s) horizontal wind speed (m/s)
  • zm Measurement heights of eddy covariance (m)
  • zmi Measurement heights of additional wind profiles (m)
  • hc Canopy height (m)
  • LAI Leaf area index (m2/m2)

We are seeking data especially from sites with high-precision wind profile measurements, in addition to the EC measurements, so we can adopt the conventional wind-profile approach to validate estimates from single-level methods. We prefer the length of each dataset to be 1+ year , or at least to cover the entire growing season, so that we are able to test seasonal dynamics estimates. To be included in these syntheses, please submit data by September 15, 2016.

For registered AmeriFlux sites: upload files through the AmeriFlux data upload. In the file description, specify: “Data for roughness syntheses.”

For alternative submission: Email data files directly to Housen Chu (, or share them with Housen via Dropbox.

Proposal for Aerodynamic Roughness Parameters across Flux Sites (view pdf)

  • Cross-site evaluation of methods for the estimation of aerodynamic roughness parameters from flux-tower data
    Housen Chu* and Dennis D Baldocchi, ESPM, University of California, Berkeley, CA, USA; Cristina Poindexter, DCE, California State University, Sacramento, CA, USA; Michael Abraha, GLBRC, Michigan State University, East Lansing, MI, USA


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