Sea state information is critical for a broad range of human activities (e.g. shipping, marine energy, marine engineering) most of them being concentrated along the coastal zone. Satellite altimeter records of significant wave heights (SWH) represent the largest source of sea state observations available to date. However, the quality of altimeter observations is reduced in the coastal zone due to surface heterogeneity within the radar signal footprint. Major difficulties to assess the performance of coastal altimetry in the coastal zone are the reduced number of valid altimeter records and the increased sea state variability, which have recently fostered the development of new methods to pair and compare nearby altimeter and buoy data. In this study, we use a high-resolution numerical wave model implemented over the European coastal waters in order to characterize the spatial variability of sea states in the proximity of coastal in situ buoys, we explore different model-based data-pairing methods to account for coastal sea state variability and we assess their impact on the validation of Sentinel-3A 20Hz SWH measurements. Three Sentinel-3A processing modes are considered: the pseudo low rate mode processing, the SAR processing and the Low Resolution with Range Migration Correction (LR-RMC) processing. Our results indicate major impacts of data-pairing methods on the Sentinel-3A coastal validation and reveals the contribution of more frequent low SWH conditions, poorly resolved by radar altimeters, in the coastal zone as an additional source of errors in coastal altimetry.

中文翻译：

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高度计-浮标数据配对方法对 Sentinel-3A 沿海显著波高验证的影响


海况信息对于广泛的人类活动（例如航运、海洋能源、海洋工程）至关重要，其中大部分活动都集中在沿海地区。有效波高 （SWH） 的卫星高度计记录是迄今为止可用的最大海况观测来源。然而，由于雷达信号足迹内的表面异质性，沿海地区的高度计观测质量会降低。评估沿海地区沿海测高性能的主要困难是有效高度计记录数量的减少和海况变化的增加，这最近促进了配对和比较附近高度计和浮标数据的新方法的发展。在这项研究中，我们使用在欧洲沿海水域实施的高分辨率数值波浪模型来表征沿海原位浮标附近海况的空间变化，我们探索了不同的基于模型的数据配对方法来解释沿海海况变化，并评估它们对 Sentinel-3A 20Hz SWH 测量验证的影响。考虑了三种 Sentinel-3A 处理模式：伪低速率模式处理、SAR 处理和带范围偏移校正的低分辨率 （LR-RMC） 处理。我们的结果表明数据配对方法对 Sentinel-3A 沿海验证的重大影响，并揭示了沿海地区更频繁的低 SWH 条件（雷达高度计无法分辨）的贡献是沿海测高误差的额外来源。