Assessment of satellite altimetry SWH measurements by in situ observations within 25 km from the coast

IF 2.2 3区 地球科学 Q2 OCEANOGRAPHY Ocean Dynamics Pub Date : 2024-01-18 DOI:10.1007/s10236-024-01597-9
Isabel Bué, Gil Lemos, Álvaro Semedo, João Catalão
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Abstract

Satellite radar altimeters (SA) have been providing ocean wind and wave measurements for over 35 years. These data have been used for modelling data assimilation, improving wind and wave climatology, and determining long-term trends of the oceanic wave parameters. Fixed observational sites (in situ locations), such as buoys, have provided reliable wave observations since the early 1970s. However, their positioning is inhomogeneous, mainly in the Northern Hemisphere, and only provides point measurements. SA significant wave height (SWH) measurements have been proven as accurate as in situ observations, particularly in the open ocean. Progress in coastal altimetry sensors, upgraded data corrections, and new extraction algorithms have recently improved the quality of SA measurements closer to the coast. This study evaluates the performance of 12 SA missions from 1985 to 2020, particularly in nearshore areas. The SA SWH along-track measurements are compared with observations from 402 in situ locations, distributed worldwide within 25 km of the coastline. Results indicate a slight overestimation from the 12 SA missions, mainly for lower sea states (under 2 m high) and closer to the coast (0 to 10 km). The Sentinel-3 mission showed the highest percentages of valid measurements near the coast and presented 72.66% of collocated in situ data. This SA mission has shown the best overall performance closer to the coast, with biases, correlation coefficient, and root-mean-squared error of 0.23 m, 0.85 m, and 0.50 m, respectively. SA undersampling in coastal areas is present and can lead to underestimation during extreme wave events. The cross-validation of the wave data in two regional analyses conducted during periods of severe wave conditions is evaluated for the new altimeters’ generation.

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通过距海岸 25 公里范围内的实地观测评估卫星测高 SWH 测量值
卫星雷达测高仪(SA)提供海洋风浪测量数据已有 35 年之久。这些数据被用于模拟数据同化、改进风浪气候学以及确定海洋波浪参数的长期趋势。自 20 世纪 70 年代初以来,浮标等固定观测点(原位)提供了可靠的波浪观测数据。不过,它们的定位不均匀,主要在北半球,而且只能提供点测量。实践证明,南亚显波高度(SWH)的测量结果与现场观测结果一样准确,特别是在 开阔海域。近来,沿岸测高传感器的进步、数据修正的升级和新的提取算法,提高了近岸 SA 测量的质量。本研究评估了 1985-2020 年间 12 次 SA 任务的性能,特别是近岸区域的性能。将 SA SWH 沿轨迹测量值与分布在全球海岸线 25 公里范围内的 402 个原地观测点的观测值进行了比较。结果表明,12 个 SA 任务的估算结果略有偏高,主要是在较低海况(高度低于 2 米)和靠近海岸(0 至 10 公里)的地区。哨兵-3 号任务显示海岸附近有效测量的百分比最高,并提供了 72.66%的现场数据。在靠近海岸的地区,SA 任务的总体性能最好,偏差、相关系数和均方根误差分别为 0.23 米、0.85 米和 0.50 米。沿海地区存在 SA 取样不足的现象,在极端波浪事件中可能导致低估。在两次区域分析中,在波浪条件恶劣的时期对波浪数据进行了交叉验证,以评估 新一代高度计的性能。
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来源期刊
Ocean Dynamics
Ocean Dynamics 地学-海洋学
CiteScore
5.40
自引率
0.00%
发文量
37
审稿时长
6-12 weeks
期刊介绍: Ocean Dynamics is an international journal that aims to publish high-quality peer-reviewed articles in the following areas of research: Theoretical oceanography (new theoretical concepts that further system understanding with a strong view to applicability for operational or monitoring purposes); Computational oceanography (all aspects of ocean modeling and data analysis); Observational oceanography (new techniques or systematic approaches in measuring oceanic variables, including all aspects of monitoring the state of the ocean); Articles with an interdisciplinary character that encompass research in the fields of biological, chemical and physical oceanography are especially encouraged.
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