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首页> 外文期刊>Agricultural Water Management >Satellite-based NDVI crop coefficients and evapotranspiration with eddy covariance validation for multiple durum wheat fields in the US Southwest
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Satellite-based NDVI crop coefficients and evapotranspiration with eddy covariance validation for multiple durum wheat fields in the US Southwest

机译：基于卫星的NDVI作物系数和evapotranspiration，对美国西南多杜兰麦田的涡流协方差验证

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A three-year study was conducted to assess the ability of satellite-based vegetation index (VI) images to track evapotranspiration over wheat. While the ability of using VIs, notably with the Normalized Difference Vegetation Index (NDVI), to track vegetation growth has been well established, the operational capability to accurately estimate the crop coefficient (K-c) and crop evapotranspiration (ETc) at farm-scale from spaceborne platforms has not been widely studied. The study evaluated wheat ET over 7 sites between 2016 and 2019 in Yuma and Maricopa, Arizona, USA estimated by using Sentinel 2 and Venus satellites to map NDVI time-series for entire wheat cropping seasons, December to June. The basal crop coefficient (K-cb) was modeled by the NDVI time-series and the daily FAO56 reference ETo was obtained by near-by weather network stations. Eddy covariance (EC) stations in each field observed ETc during the same seasonal periods, and applied irrigation amounts were logged. The experiment found that remote sensing of NDVI and modeled K-cb accurately estimated K-c and crop ET during mid-season through senescence in most cases. However, NDVI-based estimation performed less well during early season (<60 days after planting), when observed ETc was highly variable due to frequent rain and irrigation at low crop cover. Mid-season K-c values observed for the seven wheat fields were from 0.92 to 1.14, and end of season K-c values ranged from about 0.20 to 0.40, in close agreement to values reported elsewhere. Seasonal VI-based transpiration and ETc values ranged from 467 to 618 mm, closely agreeing with seasonal EC data, which ranged 499-684 mm. Using the Venus sensor, the study in Maricopa in 2019 revealed that when augmented by a background soil water balance model, water stressed wheat can be detected mid-season with NDVI. This capability is specifically due to the sensor's ability to provide well-calibrated images every 2 days. Findings from this study will help farmers, irrigators, and water managers use and understand the capabilities of visible near infrared remote sensing to track ETc from space.
机译：进行了为期三年的研究，以评估卫星植被指数（VI）图像跟踪小麦蒸散的能力。虽然使用VIS的能力，特别是对于归一化差异植被指数（NDVI）进行追踪植被生长，但是在农业规模中准确估计作物系数（KC）和作物蒸散（ETC）的操作能力星载平台尚未被广泛研究过。该研究评估了2016年和2019年在2016年至2019年在尤马和Maricopa，美国亚利桑那州，通过使用哨兵2和金星卫星来映射NDVI时间系列，为整个小麦种植季节映射到6月。基础作物系数（K-CB）由NDVI时间序列建模，每日FAO56参考ETO通过近天气网站获得。在相同的季节性期间观察到每个领域的EDDY协方差（EC）站点，并记录了应用灌溉量。实验发现，在大多数情况下，通过衰老在季节中遥感NDVI和建模的K-CB准确地估计K-C和作物等。然而，在初季期间的基于NDVI的估计较少（种植后的<60天），当观察到的等等由于低作物覆盖的频繁的雨水和灌溉而感到高度变化。为七个麦田观察到的季节K-C值为0.92至1.14，并且季节K-C值的结束范围为约0.20至0.40，密切协议到其他地方报告的价值。季节性VI的蒸腾蒸腾和等等价值从467到618 mm，与季节性EC数据密切合法，范围为499-684毫米。使用金星传感器，2019年的MariCopa的研究显示，当由背景土壤水平模型增强时，含水浓度的小麦可以用NDVI检测。这种功能专门由于传感器每2天提供校准图像的能力。本研究的调查结果将帮助农民，灌溉者和水管理者使用，并了解可见的近红外遥感到轨道等的可见功能。

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