The scintillation method tested over a dry vineyard area |
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| Authors: | H A R De Bruin B J J M Van Den Hurk W Kohsiek |
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| Institution: | (1) Department of Meteorology, Wageningen Agricultural University, 6701 AP Wageningen, The Netherlands;(2) Royal Netherlands Meteorological Institute, PO Box 201, De Bilt, the Netherlands |
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| Abstract: | Measurements of a scintillometer device mounted at 4 m above a dry vineyard area in La Mancha, Spain, are used to obtain an average sensible heat flux densityH. Averaging is over a rectangular area determined by the distance between the scintillometer light source and receptor (875 m) and some upwind distance governed by the horizontal wind speed perpendicular to that line. Using similarity relations obtained from La Crau, a good correspondence betweenH measured with the scintillometer and an eddy-correlation device in the centre of a vineyard is obtained. The friction velocityu
* was either measured directly using a sonic anemometer or obtained indirectly from two wind speeds and known values of the roughness length zo and displacementd. The free convection formulation underestimates the sensible heat flux by about 30%. This is due to a significant contribution of mechanically generated turbulence to the total turbulent transport, which was caused by relatively strong winds and rough terrain. |
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