Accurate and timely inland waterbody extent and location data are foundational information to support a variety of hydrological applications and water resources management. Recently, the Cyclone Global Navigation Satellite System (CYGNSS) has emerged as a promising tool for delineating inland water due to distinct surface reflectivity characteristics over dry versus wet land which are observable by CYGNSS’s eight microsatellites with passive bistatic radars that acquire reflected L-band signals from the Global Positioning System (GPS) (i.e., signals of opportunity). This study conducts a baseline 1-km comparison of water masks for the contiguous United States between latitudes of 24°N-37°N for 2019 using three Earth observation systems: CYGNSS (i.e., our baseline water mask data), the Moderate Resolution Imaging Spectroradiometer (MODIS) (i.e., land water mask data), and the Landsat Global Surface Water product (i.e., Pekel data). Spatial performance of the 1-km comparison water mask was assessed using confusion matrix statistics and optical high-resolution commercial satellite imagery. When a mosaic of binary thresholds for 8 sub-basins for CYGNSS data were employed, confusion matrix statistics were improved such as up to a 34% increase in F1-score. Further, a performance metric of ratio of inland water to catchment area showed that inland water area estimates from CYGNSS, MODIS, and Landsat were within 2.3% of each other regardless of the sub-basin observed. Overall, this study provides valuable insight into the spatial similarities and discrepancies of inland water masks derived from optical (visible) versus radar (Global Navigation Satellite System Reflectometry, GNSS-R) based satellite Earth observations.

中文翻译：

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CYGNSS、MODIS、Landsat 和商业卫星图像的内陆水域观测数据的空间比较

准确、及时的内陆水体范围和位置数据是支持各种水文应用和水资源管理的基础信息。最近，旋风全球导航卫星系统 (CYGNSS) 已成为描绘内陆水域的有前途的工具，因为干地与湿地的表面反射率特征不同，CYGNSS 的八颗微卫星配备无源双基地雷达，可获取反射的 L 波段信号，可观测到这些特征来自全球定位系统（GPS）（即机会信号）。本研究使用三个地球观测系统对 2019 年美国本土纬度 24°N-37°N 之间的水罩进行基线 1 公里比较：CYGNSS（即我们的基线水罩数据）、中分辨率成像光谱辐射计 (MODIS)（即陆地水掩模数据）和 Landsat 全球地表水产品（即 Pekel 数据）。使用混淆矩阵统计和光学高分辨率商业卫星图像评估 1 公里比较水罩的空间性能。当对 CYGNSS 数据采用 8 个子流域的二元阈值镶嵌时，混淆矩阵统计数据得到了改进，例如 F1 分数增加了 34%。此外，内陆水域与流域面积之比的绩效指标表明，无论观察到哪个子流域，CYGNSS、MODIS 和 Landsat 估算的内陆水域面积彼此之间的误差都在 2.3% 以内。总体而言，这项研究为基于光学（可见光）与基于雷达（全球导航卫星系统反射计，GNSS-R）的卫星地球观测得出的内陆水掩模的空间相似性和差异提供了宝贵的见解。