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On nighttime turbulent exchange within and above a sloped vineyard

University of British Columbia

High frequency three-dimensional wind and distributed temperature measurements were taken over a ~7˚ vineyard slope in the Southern Okanagan Valley, British Columbia, Canada, during three weeks in July 2016. Approximately 17% of the nighttime is characterised by drainage flow along the local slope. Drainage conditions are characterised by inverted temperatures beginning around z/hc = 0.39, where z is the height above ground level (AGL) and hc is the canopy height (~2.3 m AGL), and near-surface lapses. A jet maximum is observed around z/hc = 1.65, while a weak inflection point is observed near the canopy top, suggesting influence from both drainage layer and canopy layer dynamics on the turbulent field. The greatest observed fluxes in both the stream-wise momentum flux and the sensible heat flux are near the top of the canopy, consistent with the location of the inflection point. Calculated two-point length scales from distributed temperature measurements reveal that turbulent structures are smallest near the canopy top. Conditional sampling of the 3-D ultrasonic wind components and acoustic temperature indicate that a large fraction of canopy layer transport is driven by canopy-top turbulence, with sweeps dominating over ejections, particularly at z/hc = 0.65. Results presented here are important both for nighttime vineyard management techniques and for further understanding on particle dispersion.

Text

2017-08-10

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/62574

Geography

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/