Nowadays, Sentinel-1 (S-1) synthetic aperture radars (SARs) operating in wave mode and the real aperture radar (RAR) called Surface Waves Investigation and Monitoring (SWIM) onboard the China-France Oceanography SATellite (CFOSAT) are the only two kinds of spaceborne radars providing directional ocean wave information globally. To quantify the absolute uncertainties in the swell wave heights of a specific wave system (Hss) observed from these two spaceborne sensors, a triple colocation error model is exploited via WaveWatch III (WW3) wave model hindcasts for the first time. After implementing spatiotemporal collocation, cross-assigning swell partitions, and rejecting suspicious data, a database of the optimal-matched Hss triplets (S-1, SWIM, and WW3) is determined over a one-year period (June 2020–June 2021). Qualitatively, traditional dual intercomparisons indicate the inconsistency between the Hss from both SAR and RAR radars in terms of systematic biases. Furthermore, the triple collocated error analysis quantitatively reveals that, at a global scale, SWIM onboard CFOSAT has the least uncertainty in Hss [~0.2-m root mean square error (RMSE) and ~11% scatter index (SI)] compared with S-1 SAR (0.35–0.50-m RMSE and 17%–26% SI depending on incidence modes) and WW3, under the assumption that the random errors of the three data sources are independent, indicating that the newly launched SWIM instrument is an invaluable resource of directional wave information for the scientific community. The results are discussed with respect to regional error characteristics along with a feasible explanation of error sources. The findings could be helpful for better understanding and synergistically exploiting the Hss datasets from these two spaceborne radars.

中文翻译：

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通过三重搭配量化 CFOSAT SWIM 和 Sentinel-1 SAR 观测到的分区涌浪高度的不确定性


目前，Sentinel-1（S-1）以波动模式运行的合成孔径雷达（SAR）和中法海洋卫星（CFOSAT）上的表面波调查和监测（SWIM）真实孔径雷达（RAR）是唯一的两种星载雷达提供全球定向海浪信息。为了量化从这两个星载传感器观测到的特定波浪系统 (Hss) 的涌浪高度的绝对不确定性，首次通过 WaveWatch III (WW3) 波浪模型后报利用了三重共置误差模型。在实施时空搭配、交叉分配膨胀分区并拒绝可疑数据后，在一年的时间内（2020年6月至2021年6月）确定了最佳匹配的Hss三元组（S-1、SWIM和WW3）的数据库。定性地讲，传统的双重比对表明 SAR 和 RAR 雷达的 Hss 在系统偏差方面存在不一致。此外，三重配置误差分析定量表明，在全球范围内，与 S 相比，CFOSAT 机载 SWIM 在 Hss 方面的不确定性最小 [~0.2-m 均方根误差 (RMSE) 和~11% 散射指数 (SI)] -1 SAR（0.35–0.50-m RMSE 和 17%–26% SI，具体取决于发生模式）和 WW3，假设三个数据源的随机误差是独立的，这表明新推出的 SWIM 仪器是无价的科学界的定向波信息资源。讨论了区域误差特征以及误差源的可行解释的结果。这些发现可能有助于更好地理解和协同利用这两个星载雷达的 Hss 数据集。