Abstract Information on crop phenological development stages such as emergence, flowering, fruiting, maturing and senescence is essential for crop production surveillance and yield prediction. It has long been related to optical spectral signatures such as the Normalized Difference Vegetation Index (NDVI) or spectral shifts in the red-edge range. In recent years, more efforts have been made to explore the sensitivity of Synthetic Aperture Radar (SAR), particularly polarimetric SAR signatures, to crop biophysical parameters or phenological stages. In this study, phenological metrics of canola (Brassica napus) and spring wheat (Triticum spp.) are related with temporal evolution of polarimetric SAR parameters derived from the C-band RADARSAT-2 full polarimetric SAR data. Both crops are very common in north eastern Ontario, Canada, but have very anatomically different development processes. From multi-temporal RADARSAT-2 data acquired in three consecutive years (2012–2014), significant correlations were observed between a number of SAR polarimetric parameters and the growth parameters of both crops. Strong correlation was observed between plant height and the Alpha angle of the Cloude-Pottier decomposition, with the R2 of 0.91 and 0.66 for canola and wheat, respectively. The R2 increased when the polarimetric parameters were smoothed in the time domain (R2 of 0.98 for canola and 0.88 for wheat). Strong correlation was also observed for the two crops between the effective leaf area index (LAIe) and the Beta angle, and between days-after-seeding (DAS) and a combination of the Alpha and the Beta angles. These findings show that multi-temporal C-band polarimetric SAR parameters could be used for tracking crop phenological development stages.

中文翻译：

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使用多时相极化 Radarsat-2 数据跟踪作物物候发育

摘要 作物物候发育阶段的信息，如出苗、开花、结果、成熟和衰老，对于作物生产监测和产量预测至关重要。长期以来，它一直与光谱特征有关，例如归一化差异植被指数 (NDVI) 或红边范围内的光谱偏移。近年来，已经做出更多努力来探索合成孔径雷达 (SAR)，特别是极化 SAR 特征对作物生物物理参数或物候阶段的敏感性。在这项研究中，油菜（Brassica napus）和春小麦（Triticum spp.）的物候指标与从 C 波段 RADARSAT-2 全极化 SAR 数据导出的极化 SAR 参数的时间演变有关。这两种作物在加拿大安大略省东北部非常常见，但在解剖学上有非常不同的发展过程。从连续三年（2012-2014 年）获得的多时相 RADARSAT-2 数据中，观察到许多 SAR 极化参数与两种作物的生长参数之间存在显着相关性。在植物高度和 Cloude-Pottier 分解的 Alpha 角之间观察到很强的相关性，双低油菜籽和小麦的 R2 分别为 0.91 和 0.66。当极化参数在时域中平滑时，R2 增加（油菜的 R2 为 0.98，小麦为 0.88）。还观察到两种作物的有效叶面积指数 (LAIe) 与 Beta 角之间以及播种后天数 (DAS) 与 Alpha 和 Beta 角的组合之间存在强相关性。