Encouraged by the necessity to better understand the water use in this woody crop, a study was carried out in a commercial drip-irrigated young almond orchard to quantify and monitor the crop evapotranspiration (ET_c) and its partitioning into tree canopy transpiration (T) and soil evaporation (E), to list and analyze single and dual crop coefficients, and to extract relationships between them and the vegetation fractional cover (f_c) and remote-sensing-derived vegetation indices (VI_s). A Simplified Two-Source Energy Balance (STSEB) model was applied, and the results were compared to ground measurements from a flux tower. This study comprises three consecutive growing seasons from 2017 to 2019, corresponding to Years 2 to 4 after planting. Uncertainties lower than 50 W m⁻² were obtained for all terms of the energy balance equation on an instantaneous scale, with average estimation errors of 0.06 mm h⁻¹ and 0.6 mm d⁻¹, for hourly and daily ET_c, respectively. Water use for our young almond orchard resulted in average mid-season crop coefficient (K_{c mid}) values of 0.30, 0.33, and 0.45 for the 2017, 2018, and 2019 growing seasons, corresponding to f_c mean values of 0.21, 0.35, and 0.39, respectively. Average daily evapotranspiration for the same periods resulted in 1.7, 2.1, and 3.2 mm d⁻¹. The results entail the possibility of predicting the water use of any age almond orchards by monitoring its biophysical parameters.

中文翻译：

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应用双源表面能量平衡模型监测滴灌年轻杏仁园中的作物蒸发蒸腾和蒸腾/蒸发分配

出于更好地了解这种木本作物用水的必要性，在商业滴灌年轻杏仁果园中进行了一项研究，以量化和监测作物蒸发蒸腾量 (ET _c ) 及其在树冠蒸腾量 (T) 中的分配和土壤蒸发 (E)，列出和分析单作物系数和双作物系数，并提取它们与植被覆盖率 (f _c ) 和遥感衍生植被指数 (VI _{s) 之间的关系}）。应用了简化的双源能量平衡 (STSEB) 模型，并将结果与​​磁通塔的地面测量结果进行了比较。本研究包括从 2017 年到 2019 年的三个连续生长季节，对应于种植后的第 2 年到第 4 年。对于瞬时尺度上的能量平衡方程的所有项，获得低于50 W m ^{-2 的}不确定性，对于每小时和每天ET _{c 的}平均估计误差分别为0.06 mm h ^-1和0.6 mm d ^-1。我们年轻杏仁果园的用水导致2017、2018 和 2019 年生长季节的平均中期作物系数 (K _{c mid} ) 值为 0.30、0.33 和 0.45，对应于 f _c平均值分别为 0.21、0.35 和 0.39。同一时期的平均每日蒸散量为 1.7、2.1 和 3.2 mm d ^-1。结果意味着可以通过监测其生物物理参数来预测任何年龄杏仁果园的用水量。