The use of remote sensing for reliable estimation of net radiation and its components: a case study for contrasting land covers in an agricultural hotspot of the Brazilian semiarid region
The use of remote sensing for reliable estimation of net radiation and its components: a case study for contrasting land covers in an agricultural hotspot of the Brazilian semiarid region
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DOI：
10.1016/j.agrformet.2020.108052
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发表时间：
2020-09
影响因子：
6.2
通讯作者：
T. Ferreira;B. B. Silva-B.;M. Moura;A. Verhoef;R. Nóbrega
中科院分区：
文献类型：
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作者：
T. Ferreira;B. B. Silva-B.;M. Moura;A. Verhoef;R. Nóbrega
这项研究的目的是确定与利用遥感数据对净辐射及其组成部分进行时空估计有关的不确定性。地理重点是灌溉农业热点的巴西半干旱地区，我们也调查的影响，对比土地覆盖类型上涌辐射平衡组件，因此净辐射。根据OLI/TIRS-Landsat-8图像和关键天气变量，估计了净辐射的瞬时值（Rn）和日值（Rn，24）。此外，我们评估了两个下涌短波（Rsw）模型、十个下涌长波辐射（Rlw）模型以及两个推导Rn的模型，24。每个模型的准确性进行了评估，从研究质量传感器安装在微气象塔获得的辐射测量。对于Rsw、Rlw和Rn，分别发现艾伦模型、Duarte模型和De Bruin模型的最佳性能。对比的土地利用类型表现出显着差异的生物物理变量和辐射特性，影响Rn。灌溉作物的温度平均绝对值比原始caatinga高0.01-0.03度，而地表温度LST低3-5度。然而，这两个明显不同的表面类型的Rn是相似的，作为一个相当低的表面发射率在caatinga的结果。对于牧场，的Rupdo，LST，因此，上升流辐射有更大的值比发现的caatinga，这导致Rn值降低。城市地区的Rn值最低，这主要是由于它们的高Rn值。我们表明，当现场净辐射数据不可用，遥感数据结合更容易获得的现场天气数据可以用来获得Rn的时空估计。这有助于确定人类活动对地表辐射的影响，并最终确定能量平衡，包括短期的季节性影响和长期影响。
This study aims to ascertain the uncertainties related to the spatiotemporal estimation of net radiation, and its components, using remote sensing data. Geographical focus is an irrigated agricultural hotspot of the Brazilian semiarid region, for which we also investigate the impact that contrasting land-cover types have on the upwelling radiation balance components, and hence on net radiation. Instantaneous (Rn) and daily (Rn,24) values of net radiation were estimated based on OLI/TIRS-Landsat-8 images and key weather variables. In addition, we evaluated two models for downwelling shortwave (Rsw), ten models for downwelling longwave radiation (Rlw), and two models for derivation of Rn,24. The accuracy of each model was evaluated with radiation measurements obtained from research quality sensors installed in micrometeorological towers. The best performances were found for the Allen model, Duarte model, and De Bruin model for Rsw, Rlw, and Rn,24, respectively. The contrasting land-use types exhibited substantial differences in the biophysical variables and radiative properties that affect Rn. The albedo for the irrigated crops has average absolute values that are 0.01–0.03 greater than those found for the pristine caatinga, whereas the land surface temperature, LST, is 3–5 degrees smaller. However, Rnfor these two distinctly different surface types was similar, as a result of a considerably lower surface emissivity in the caatinga. For rangeland, the albedo, LST, and hence the upwelling radiation had greater values than those found for the caatinga, which caused reduced values of Rn. The urban areas exhibited the lowest values of Rn, mainly as a consequence of their high albedo values. We show that when in-situ net radiation data are not available, remote sensing data combined with more readily available in-situ weather data can be used to derive spatiotemporal estimates of Rn. This facilitates the identification of anthropogenic impacts on the radiation at the land-surface and ultimately the energy balance, including the short-term seasonal and long-term effects.