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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Disease and Pest Management Research Unit » Research » Publications at this Location » Publication #382908
Research Project: Integrated Disease Management of Exotic and Emerging Plant Diseases of Horticultural Crops

Location: Horticultural Crops Disease and Pest Management Research Unit

Title: Quantifying turbulence heterogeneity in a vineyard using eddy-covariance and scintillometer measurements

Author
item PERELET, ALEXEI - University Of Utah
item WARD, HELEN - University Of Innsbruck
item STOLL, ROB - University Of Utah
item Mahaffee, Walter - Walt
item PARDYJAK, ERIC - University Of Utah

Submitted to: Boundary Layer Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/4/2022
Publication Date: 6/22/2022
Citation: Perelet, A.O., Ward, H.C., Stoll, R., Mahaffee, W.F., Pardyjak, E. 2022. Quantifying turbulence heterogeneity in a vineyard using eddy-covariance and scintillometer measurements. Boundary Layer Meteorology. 184:479-504. https://doi.org/10.1007/s10546-022-00714-9.
DOI: https://doi.org/10.1007/s10546-022-00714-9

Interpretive Summary: In order to further develop improved models for predicting various vineyard parameters (e.g. water use, pest and disease development, etc) and enhance the resolution of current decision aides in time and space, an improved understanding of how to measure variability in vineyard is needed. This research compares sctillometery to several eddy-covariance stations to examine temperature and humidity differences at the vineyard scale. We found that the underlying theory for the use of sctillometery to measure the change of temperature and humidity over a heterogeneous vineyard was valid. The sctillometer accurately captured the variability in time and space at the vineyard scale. These data indicate that we can could use sctillometery to examine larger areas and accurately estimate changes in temperature and humidity. this approach will likely improve estimates of other parameters derived from these values at the sub-managment unit scale.

Technical Abstract: Scintillometry is a non-invasive measurement technique for acquiring spatially-averaged surface heat and moisture fluxes in areas where setting up arrays of instruments can be expensive and logistically difficult. As a path-averaged measurement, scintillometry is a valuable tool for measuring integrated atmospheric turbulence over agricultural terrain where in-situ measurements would interfere with farm operations. For this study, a two-wavelength scintillometry system was deployed at an effective height of 7.3 m above ground spanning 749 m over an active vineyard with a canopy height of 2.15 m. In order to provide points of comparison for the scintillometer fluxes, four eddy-covariance stations were placed within the vineyard to represent the spatial heterogeneity. This allowed for the assessment of whether the path-averaged structure parameters of temperature, CT^2S, and humidity, Cq^2, adhered to Monin-Obukhov similarity theory (MOST). We derived a metric, D to quantify the deviation from homogeneity that describes the non-linear effects in MOST linking structure parameters and fluxes. This deviation metric gives a physical meaning to the apparent overestimation of scintillometry seen in many studies. It facilitates the identification of periods when the non-linear effects will be minimal. Through D, we show that the vineyard is homogeneous and use another dataset to emphasize the applicability of Dto more heterogeneous environments. Footprint differences can explain the discrepancies seen between scintillometry and eddy-covariance in this set-up.