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Parameterization of a two-layer model for estimating vineyard evapotranspiration using meteorological measurements

Ortega-Farias, S., Poblete-Echeverría, C., Brisson, N.
Agricultural and forest meteorology 2010 v.150 no.2 pp. 276-286
Vitis vinifera, grapes, fruit crops, vineyards, evapotranspiration, estimation, meteorological parameters, microirrigation, solar radiation, heat transfer, soil temperature, model validation, soil water content, Chile
The Shuttleworth and Wallace (SW) model with variable canopy resistance was evaluated to estimate evapotranspiration (ETv) from a drip-irrigated Merlot (Vitis vinifera L.) vineyard trained on a vertical shoot-positioned (VSP) system. This vineyard is located in the Talca Valley, Region del Maule, Chile (35°25′ LS; 71°32′ LW; 125m a.s.l). The performance of the SW model was evaluated using the eddy-covariance method on a 30min time interval. Also, sub-models to estimate net radiation (Rn) and soil heat flux (G) were used in the SW model. A good agreement between observed and estimated values of Rn was found with a root mean square error (RMSE) of 33Wm⁻² and a mean absolute error (MAE) of 24Wm⁻². Also, the SW model was able to estimate latent heat flux with RMSE and MAE of 34 and 21Wm⁻², respectively. On a daily basis, results indicate that the SW model was able to predict the ETv with RMSE and MAE values of 0.51 and 0.41mmd⁻¹, respectively. These results suggest that it is possible to directly estimate ETv over unstressed grapevines using meteorological data and soil moisture measurements.