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首页> 外文会议>Remote Sensing for Agriculture, Ecosystems, and Hydrology >Improvement of the Triangle method for soil moisture evaluation by adding a third index: albedo or Cellulose Absorption Index
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Improvement of the Triangle method for soil moisture evaluation by adding a third index: albedo or Cellulose Absorption Index

机译：添加第三指数的土壤水分评价三角形方法的改进：Albedo或纤维素吸收指数

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摘要

Vegetation and soil temperatures have long been recognized as an indicator of water availability. When plotting the two-dimensional distribution of temperature and vegetation index (T-VI) corresponding to an area with well distributed vegetation cover and moisture content, one gets a triangular or trapezoidal shape. Iso-moisture lines range between two edges of the distribution: the dry edge and the wet edge. This description is based on a simplified representation of the thermal and radiative properties of the soil/vegetation structure and of the heat and mass transfer. A large number of parameters, in addition to soil moisture, are actually influencing the apparent soil/canopy temperature. Stretching the temperature distribution along only one dimension like the VI is indeed not enough for allowing an unambiguous determination of soil moisture. We propose to improve the identifiability of soil moisture by introducing an additional observable parameter: albedo or CAI (Cellulose Absorption Index). Albedo was chosen to separate areas according to the absorbed solar radiation whereas CAI was chosen to separate areas according to the fraction of senescent vegetation. The aim of this study is to analyze the benefit of adding a third index to the classical T-VI empirical method for soil moisture mapping. The proposed procedures were applied on remote sensing data obtained during two airborne campaigns: HyEurope 2007 and AgriSAR 2006. In the first case, when applying the 2D trapezoid method, the coefficient of determination between the inferred moisture index and the gravimetric moisture content reaches 0.61. It slightly diminishes to 0.59 when adding albedo whereas it increases to 0.69 when adding CAI instead. Therefore adding albedo doesn't seem to provide an improvement, at least for the considered cropland. The introduction of the Cellulose Absorption Index seems to be more promising. The crops during AgriSAR 2006 campaign presented in July a too high LAI whereas the soil surface was generally very dry. These conditions prevented to draw any significant conclusion. Better results are expected to be met for areas presenting lower vegetation cover as for example semi-arid regions.
机译：植被和土壤温度长期被认为是水可用性的指标。当绘制对应于具有良好分布植被覆盖和水分含量的区域的温度和植被指数（T-VI）的二维分布时，可以获得三角形或梯形的形状。 ISO水分线范围在分布的两个边缘之间：干边缘和湿边。该描述基于土壤/植被结构的热和辐射性能和热量和传质的简化表示。除了土壤水分之外，大量参数实际上是影响表观土壤/冠层的温度。仅仅像VI那样只拉伸温度分布，确实不足以允许明确测定土壤水分。我们建议通过引入额外的可观察参数来提高土壤水分的可识别性：Albedo或Cai（纤维素吸收指数）。根据吸收的太阳辐射选择了Albedo，而CAI被选中以根据衰老植被的一部分分开区域。本研究的目的是分析向土壤水分测绘的经典T-VI实证方法添加第三指数的益处。上在两个空气运动而获得的遥感数据被应用所提出的程序：HyEurope 2007和2006 AgriSAR在第一种情况，在应用二维梯形法时，所推断的水分指数和重量水分含量达到0.61之间确定的系数。当添加Albedo时，它稍微减少到0.59，而添加CAI时，它会增加到0.69。因此，添加Albedo似乎并未提供改善，至少对于被认为的裁剪。纤维素吸收指数的引入似乎更有前景。 Agrisar 2006活动期间的作物在七月介绍了太高的莱，而土壤表面通常非常干燥。这些条件阻止了得出任何重大的结论。预计为提出植被覆盖的区域，预计将满足更好的结果，例如半干旱地区。

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