P-band synthetic aperture radar (SAR) is sensitive to above-ground biomass (AGB) but retrieval accuracy has been shown to deteriorate in topographic areas. In boreal forest, the signal penetrates through the canopy to interact with the ground producing variations in backscatter depending on ground topography, forest structure, and soil moisture. Tomographic processing of multiple SAR images Tomographic SAR (TomoSAR) provides information about the vertical backscatter distribution. This article evaluates the use of P-band TomoSAR data to improve AGB retrievals from backscattered intensity by suppressing the backscattered signal from the ground. This approach can be used even when the tomographic resolution is insufficient to resolve the vertical backscatter profile. The analysis is based on P-band data from two campaigns: BioSAR-1 (2007) in Remingstorp, southern Sweden, and BioSAR-2 (2008) in Krycklan (KR), northern Sweden. BioSAR airborne data were also processed to correspond as closely as possible to future BIOMASS TomoSAR acquisitions, with BioSAR-2-based results shown. A power law AGB model using volumetric HV polarized backscatter performs best in KR, with training residual root mean-squared error (RMSE) of 30%–36% (27–33 t/ha) for airborne data and 38%–39% for simulated BIOMASS data. Airborne TomoSAR data suggest that both vertical and horizontal tomographic resolution are of importance and that it is possible to greatly reduce AGB retrieval bias when compared with airborne P-band SAR backscatter intensity-based retrievals. A lack of significant ground slopes in Remningstorp reduces the benefit of using TomoSAR data which performs similar to retrievals based solely on P-band SAR backscatter intensity.

中文翻译：

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评估P带TomoSAR在北方森林中生物量的回收

P波段合成孔径雷达（SAR）对地上生物量（AGB）敏感，但已证明在地形区域中检索精度会下降。在北方森林中，信号穿过树冠与地面相互作用，从而根据地面地形，森林结构和土壤湿度而产生反向散射变化。多个SAR图像的断层摄影处理断层摄影SAR（TomoSAR）提供有关垂直反向散射分布的信息。本文评估了通过抑制来自地面的反向散射信号，使用P波段TomoSAR数据来改善反向散射强度的AGB检索。即使断层扫描分辨率不足以解决垂直反向散射轮廓，也可以使用此方法。该分析基于来自两个活动的P波段数据：瑞典南部的Remingstorp的BioSAR-1（2007）和瑞典北部的Krycklan（KR）的BioSAR-2（2008）。还显示了BioSAR机载数据，以使其与未来BIOMASS TomoSAR的采购尽可能接近，并显示了基于BioSAR-2的结果。使用容积HV极化背向散射的幂律AGB模型在KR中表现最佳，对于航空数据，其训练残留均方根误差（RMSE）为30％–36％（27–33 t / ha），对于航空数据，其训练均方根误差为38％–39％模拟的BIOMASS数据。机载TomoSAR数据表明，垂直和水平断层扫描分辨率都很重要，与基于机载P波段SAR背向散射强度的检索相比，可以大大降低AGB检索偏差。