This study explores the potential of Sentinel-1 Synthetic Aperture Radar (SAR) to identify phenological phases of wheat, sugar beet, and canola. Breakpoint and extreme value analyses were applied to a dense time series of interferometric (InSAR) and polarimetric (PolSAR) features recorded during the growing season of 2017 at the JECAM site DEMMIN (Germany). The analyses of breakpoints and extrema allowed for the distinction of vegetative and reproductive stages for wheat and canola. Certain phenological stages, measured in situ using the BBCH-scale, such as leaf development and rosette growth of sugar beet or stem elongation and ripening of wheat, were detectable by a combination of InSAR coherence, polarimetric Alpha and Entropy, and backscatter (VV/VH). Except for some fringe cases, the temporal difference between in situ observations and breakpoints or extrema ranged from zero to five days. Backscatter produced the signature that generated the most breakpoints and extrema. However, certain micro stadia, such as leaf development of BBCH 10 of sugar beet or flowering BBCH 69 of wheat, were only identifiable by the InSAR coherence and Alpha. Hence, it is concluded that combining PolSAR and InSAR features increases the number of detectable phenological events in the phenological cycles of crops.

中文翻译：

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物候学发展对源自 Sentinel-1 的干涉测量和偏振测量作物特征的影响：来自 DEMMIN 研究站点的示例（德国）

本研究探讨了 Sentinel-1 合成孔径雷达 (SAR) 在识别小麦、甜菜和油菜的物候阶段方面的潜力。断点和极值分析应用于 2017 年生长季节在 JECAM 站点 DEMMIN（德国）记录的密集时间序列的干涉 (InSAR) 和极化 (PolSAR) 特征。断点和极值的分析允许区分小麦和油菜的营养阶段和繁殖阶段。使用 BBCH 尺度原位测量的某些物候阶段，例如甜菜的叶发育和莲座丛生长或小麦的茎伸长和成熟，可通过 InSAR 相干性、极化 Alpha 和熵以及反向散射 (VV/ VH)。除了一些边缘情况，实地观察与断点或极值之间的时间差异从零到五天不等。反向散射产生了产生最多断点和极值的特征。然而，某些微视域，例如甜菜 BBCH 10 的叶片发育或小麦 BBCH 69 的开花，只能通过 InSAR 相干性和 Alpha 来识别。因此，可以得出结论，结合 PolSAR 和 InSAR 特征增加了作物物候循环中可检测物候事件的数量。