The adjacency effect distorts the top-of-atmosphere (TOA) spectral signals of coastal and inland waters and is a major challenge for optical remote sensing of nearshore aquatic environments. We introduce a closed-form expression that corrects for the adjacency effect prior to atmospheric correction. The method is included in an open-source Python tool, which ingests level-1 imagery and calculates the point-spread function of the atmosphere to convolve the input imagery. For each band, the difference between the observed and convolved reflectances is used to quantify and correct for the adjacency effect, i.e., pixels are corrected to the TOA reflectance they would have if surrounded by pixels of identical reflectance. Validation was conducted for Sentinel-2 MSI and Landsat 8 OLI imagery against a global dataset of coincident in situ radiometric measurements. Results showed improved accuracy of water-leaving reflectance derived by atmospheric correction processors, including ACOLITE, POLYMER, and l2gen, when these were applied following adjacency-effect correction. For matchups within 200 m of shorelines (n = 212), adjacency-effect correction resulted in an average 16.7 % reduction in root mean square error, a 32.4 % reduction in symmetric signed percentage bias, and a 36.8 % reduction in median symmetric accuracy for the three processors. The improvements were more significant in the near-infrared (NIR) range for ACOLITE, visible wavelengths for l2gen, and evenly distributed across the visible-NIR spectrum for POLYMER. We anticipate that this physics-based approach to adjacency-effect correction will lead to improved satellite-derived aquatic products for coastal and inland waters under diverse atmospheric and aquatic conditions.

中文翻译：

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用于沿海和内陆水域遥感的传感器通用邻接效应校正


邻接效应扭曲了沿海和内陆水域的大气顶 （TOA） 光谱信号，是近岸水生环境光学遥感的重大挑战。我们引入了一个封闭式表达式，用于在大气校正之前校正邻接效应。该方法包含在开源 Python 工具中，该工具可提取 1 级影像并计算大气的点扩散函数以卷积输入影像。对于每个波段，观测反射率和卷积反射率之间的差异用于量化和校正邻接效应，即，像素被校正为它们被相同反射率的像素包围时所具有的 TOA 反射率。根据重合原位辐射测量的全球数据集，对 Sentinel-2 MSI 和 Landsat 8 OLI 影像进行了验证。结果表明，在邻接效应校正后应用大气校正处理器（包括 ACOLITE、POLYMER 和 l2gen）得出的离水反射率的准确性有所提高。对于海岸线 200 m 范围内的对决 （n = 212），邻接效应校正导致三个处理器的均方根误差平均减少 16.7%，对称有符号百分比偏差减少 32.4%，对称对称精度中位数降低 36.8%。在 ACOLITE 的近红外 （NIR） 范围内，l2gen 的可见波长以及 POLYMER 的可见光 NIR 光谱中均匀分布，改进更为显着。我们预计，这种基于物理学的邻接效应校正方法将导致在各种大气和水生条件下为沿海和内陆水域改进卫星衍生的水产品。