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Title: TURBULENCE FLUX ESTIMATES OF SENSIBLE AND LATENT HEAT NEAR SHELTERBELTS DURING LOW WIND CONDITIONS

Author
item Prueger, John
item Sauer, Thomas
item Hatfield, Jerry

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Windbreak shelterbelts are used to protect against harmful effects of high wind speeds blowing over a landscape resulting in erosion of topsoil and seedling damage by soil particulates. Shelterbelts can also affect the way solar energy is partitioned into surface heating and evaporation at the windward and lee sides of a shelterbelt. There is a scarcity of comparative evaporation measurements from windward and leeward sides of a shelterbelt. An experiment was conducted at the University of Nebraska research farm to measure evaporation and surface heating as affected by position near a shelterbelt. Results from this study show that for wheat stubble fields, evaporation under low wind conditions was slightly larger on the windward side of the shelterbelt than on the leeward side. Conversely, for an alfalfa field, no significant differences could be observed. Also, evaporation measurements near shelterbelts were found to be valid despite the close confines of a shelterbelt. This has important implications for future studies involving evaporation measurements near shelterbelts.

Technical Abstract: A study was conducted to evaluate sensible and latent heat fluxes near shelterbelts under low wind conditions using eddy correlation. The study site was located at the Agricultural Meteorological Research Center in Mead, Nebraska during the summer of 1995. A wheat stubble field and an alfalfa field surrounded by a shelterbelt 12 m in height were instrumented with surface energy balance systems using eddy correlation that were located in the windward and leeward side of the shelterbelts for both fields. Estimates of sensible and latent heat fluxes were compared for the windward and leeward sides of the shelterbelt for both surfaces. Daily sensible heat fluxes tended to be larger in the open location relative to the sheltered location while latent heat fluxes tended to be larger behind the shelterbelt. Overall surface energy balance closure during the study averaged 0.85, indicating reliable consistent estimates of turbulence flux using eddy correlation near shelterbelts.