Forest Above-Ground Biomass Estimation Using Single-Baseline Polarization Coherence Tomography with P-Band PolInSAR Data
Forest Above-Ground Biomass Estimation Using Single-Baseline Polarization Coherence Tomography with P-Band PolInSAR Data
复制标题
使用单基线偏振相干断层扫描和 P 波段 PolInSAR 数据估算森林地上生物量
作者：
Zhang Haibo;Wang Changcheng;Zhu Jianjun;Fu Haiqiang;Xie Qinghua;Shen Peng
利用合成孔径雷达（SAR）图像提取森林地上生物量（AGB）已广泛应用于全球碳循环研究。经典的SAR图像AGB反演方法主要基于后向散射系数。偏振相干层析成像（PCT）技术可以生成森林相对反射率的垂直剖面，具有提高生物量反演精度的潜力。根据相对反射率分布曲线的几何特征定义了一些参数，建立了垂直剖面与森林AGB的关系模型。但是这些参数的定义没有物理特性。其中，层析高度（TomoH）被认为是最重要的参数。而TomoH仅对应最高的体相对反射率，低于实际森林高度，影响了森林高度和AGB反演的精度。本文通过分析垂直后向散射功率损耗，引入了一个新的参数——冠层高度（Hac），用于AGB反演。然后，我们将新参数（Hac）与层析剖面的其他参数结合，构建了反演模型。选取欧洲航天局（ESA） BioSAR 2008运动在Krycklan流域上空获得的p波段极化SAR数据集，在两个不同的飞行方向上进行验证实验。结果表明，Hac在估算森林高度和AGB方面优于TomoH。该方法的反演均方根误差（RMSE）为18.325 t ha−1，使用TomoH的反演结果为21.126 t ha−1。
Forest above ground biomass (AGB) extraction using Synthetic Aperture Radar (SAR) images has been widely used in global carbon cycle research. Classical AGB inversion methods using SAR images are mainly based on backscattering coefficients. The polarization coherence tomography (PCT) technology which can generate vertical profiles of forest relative reflectivity, has the potential to improve the accuracy of biomass inversion. The relationship between vertical profiles and forest AGB is modeled by some parameters defined based on geometric characteristics of the relative reflectivity distribution curve. But these parameters are defined without physical characteristics. Among these parameters, tomographic height (TomoH) is considered as the most important one. However, TomoH only corresponds to the highest volume relative reflectivity, which is lower than the actual forest height, affecting the accuracy of forest height and AGB inversion. In this paper, we introduce a new parameter, the canopy height (Hac), for AGB inversion by analyzing the vertical backscatter power loss. Then, we construct an inversion model based on the combination of the new parameter (Hac) and other parameters from the tomographic profile. The P-band polarimetric SAR datasets of the European Space Agency (ESA) BioSAR 2008 campaign acquired over Krycklan Catchment are selected for the verification experiment at two different flight directions. The results show that Hac performs better in estimating forest height and AGB than TomoH does. The inversion root mean square error (RMSE) of the proposed method is 18.325 t ha−1, and the result of using TomoH is 21.126 t ha−1.