89th American Meteorological Society Annual Meeting

Sunday, 11 January 2009
Flow and momentum flux measurement by LIDAR over a forest canopy during NIFTY
Phoenix Convention Center
Duick Young, Indiana University, Bloomington, IN; and S. C. Pryor and R. Barthelmie
Flow and momentum flux regimes over forested heterogeneous landscapes are important as they dictate, for example; atmosphere-surface exchange of mass and the potential for wind energy applications within or close to forested terrain. In recent years, a new generation of commercial LIDARs (LIght Detection And Ranging) specifically designed for determining vertical wind and turbulence profiles have become available. These systems have the potential to yield new insights into boundary layer dynamics and to provide an alternative to the erection of expensive meteorological towers for wind farm suitability studies and profile measurements during field campaigns.

During the NIFTY (Nucleation In ForesTs) field campaign conducted in southern Indiana during May 2008 a ZEPHIR LIDAR was deployed to obtain vertical profiles of velocity (horizontal and vertical) in an expansive deciduous forest. Data from the LIDAR are being analyzed along with those derived from tower based sonic anemometers and a tethersonde system in order to:

(i) Examine the profile of wind speed over forests and to establish if they deviate from those based on surface-layer theory and specifically if adoption of an additional length scale (related to mixed layer depth) leads to improvements in the profile fits.

(ii) Evaluate the wind and turbulence profiles relative to analytical descriptions.

(iii) Evaluate the ability to derive profiles of the momentum flux from the LIDAR measurements and to compare them with those calculated from tower based sonic anemometers and a tethersonde system.

This poster presentation will focus on the application of these methods to LIDAR data and initial results.

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