Reconstruction of the Surface-Layer Vertical Structure from Measurements of Wind,Temperature and Humidity at Two Levels |
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Authors: | Juan Carlos Bergmann |
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Institution: | 1.Hamburg,Germany |
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Abstract: | A comparison of sensible heat flux derived from ultrasonic-anemometer measurements and profile-derived values shows strong
systematic bias in the stable branch. One of the two effects, large sonic-based values combined with small profile-based values,
can be explained as due to katabatic flows down the terrain slope. The other effect, large profile-based values combined with
small sonic-based values, can only partially be explained as due to intermittent turbulence. The remainder occurs at small
stability and indicates a possible systematic kink in ultrasonic-anemometer eddy-correlation values. Evaluation of the temperature-profile
parameter θ
* contributes to further clarification by reducing the systematic bias and confirming the katabatic-flow explanation. Also,
the intermittent-turbulence influence is confirmed by the θ
* evaluation, but the combination of large profile-based values with small sonic-based values does not vanish outside the more
clearly defined intermittent-turbulence region. This is associated with a strongly increased occurrence of opposite-sign sonic
values. Neutral profile values are frequently associated with considerably unstable sonic values of θ
*. |
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Keywords: | |
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