Retrieval and Multi-scale Validation of Soil Moisture from Multi-temporal SAR Data in a Semi-Arid Tropical Region
Retrieval and Multi-scale Validation of Soil Moisture from Multi-temporal SAR Data in a Semi-Arid Tropical Region
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DOI：
10.3390/rs70608128
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发表时间：
2015-06
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影响因子：
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通讯作者：
S. K. Tomer;A. Al Bitar;M. Sekhar;M. Zribi;S. Bandyopadhyay;K. Sreelash;A. Sharma;S. Corgne;
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文献类型：
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作者：
S. K. Tomer;A. Al Bitar;M. Sekhar;M. Zribi;S. Bandyopadhyay;K. Sreelash;A. Sharma;S. Corgne;
提出了一种利用多时相合成孔径雷达（SAR）数据反演地表土壤湿度的算法。该算法基于累积密度函数（CDF）对多时相RADARSAT-2后向散射系数（BC）进行变换，得到相对SM值，然后利用土壤信息将相对SM值转化为绝对SM值。该算法在印度南部的半干旱热带地区进行测试，使用30个卫星图像的RADARSAT-2，SMOS L2 SM产品，和1262 SM现场测量50个地块跨越4年。与现场数据的验证表明，所开发的算法的能力，以恢复SM与RMSE范围从0.02到0.06米（3）/米（3）的大多数地块。与SMOS SM的比较显示出良好的时间特性，RMSE约为0.05 m（3）/m（3），相关系数约为0.9。所开发的模型进行了比较，发现是优于变化检测和三角洲指数模型。该方法不需要校准任何参数，以获得相对SM，因此可以很容易地扩展到任何地区的SAR数据的时间序列。
The current study presents an algorithm to retrieve surface Soil Moisture (SM) from multi-temporal Synthetic Aperture Radar (SAR) data. The developed algorithm is based on the Cumulative Density Function (CDF) transformation of multi-temporal RADARSAT-2 backscatter coefficient (BC) to obtain relative SM values, and then converts relative SM values into absolute SM values using soil information. The algorithm is tested in a semi-arid tropical region in South India using 30 satellite images of RADARSAT-2, SMOS L2 SM products, and 1262 SM field measurements in 50 plots spanning over 4 years. The validation with the field data showed the ability of the developed algorithm to retrieve SM with RMSE ranging from 0.02 to 0.06 m(3)/m(3) for the majority of plots. Comparison with the SMOS SM showed a good temporal behaviour with RMSE of approximately 0.05 m(3)/m(3) and a correlation coefficient of approximately 0.9. The developed model is compared and found to be better than the change detection and delta index model. The approach does not require calibration of any parameter to obtain relative SM and hence can easily be extended to any region having time series of SAR data available.