Modification of the Land Surface Temperature – Vegetation Index Triangle Method for soil moisture condition estimation by using SYNOP reports
Modification of the Land Surface Temperature – Vegetation Index Triangle Method for soil moisture condition estimation by using SYNOP reports
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DOI：
10.1016/j.ecolind.2020.106823
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发表时间：
2020-12
影响因子：
6.9
通讯作者：
Karol Przeździecki;J. Zawadzki
中科院分区：
文献类型：
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作者：
Karol Przeździecki;J. Zawadzki
在局部或区域尺度上估算土壤水分状况是植被状况监测中的重要问题之一。在植被覆盖地区进行这项研究的最合适的方法之一是地表温度-植被指数(LST-VI)三角法。与利用微波波段卫星观测估算土壤水分含量的方法相比，该方法优于基于光学波段观测的逐像元土壤水分估算方法，该方法忽略了植被区蒸散量的VI和LST之间的统计关系。这项研究测试了对该方法的方法学修正，其基础是假设蒸散量取决于气温和地表温度之间的差异。用经典的三角法及其改进版计算了中欧广大地区的温度-植被干燥指数的空间分布，该指数反映了根区土壤水分。在这些计算中，NDVI和EVI指数都被用作输入数据。2米高度的气温来自SYNOP报告，地形表面温度来自MODIS数据。此外，为了方便地访问免费的SYNOP数据，作者编写了MatLab脚本。我们的结果表明，提出的修正提高了土壤水分估计的精度。通过将经典的和修正的温度-植被干燥指数值与降雨量数据进行比较，证实了这一点。
Estimation of soil moisture condition on a local or regional scale is one of the most important problems in vegetation conditions monitoring. One of the most suitable approach to do this over vegetated areas is the Land Surface Temperature – Vegetation Index (LST-VI) Triangle Method. This method estimates water content in soil which is available for plants in contrast to methods using satellite observations in the microwave band, and it is superior to pixel by pixel soil moisture methods using observations in the optical band which neglect statistical relationship between VI and LST controlling evapotranspiration on vegetated area. This study tested a methodological modification of the method based on assumption that evapotranspiration depends on the difference between the air temperature and the terrain surface temperature. The spatial distribution of Temperature-Vegetation Dryness Indices, which reflect soil moisture in the root zone was calculated for vast areas of Central Europe using the classic Triangle Method and its modified version. Both NDVI and EVI indices were used as input data in these calculations. The air temperature at 2 m height was taken from SYNOP reports, and the terrain surface temperature from MODIS data. In addition, Matlab scripts were written by the authors to allow convenient access to free SYNOP data. Our results indicate that proposed modification increases the accuracy of soil moisture estimation. This was confirmed by comparing classic and modified Temperature-Vegetation Dryness Indices values with rainfall data.