User Requirements in the Coastal Ocean for Satellite Altimetry

Dufau, Claire; Martín-Puig, Cristina; Moreno, Laura

doi:10.1007/978-3-642-12796-0_3

Cited by 8 publications

(7 citation statements)

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“…Depending on the SWH, the radius of the altimeter footprint can range from 1 km up to 7 km (e.g. for Jason missions), which enables high accuracy of the altimetry in open ocean areas, and on the other side, due to the contamination in the reflected radar altimeter signal caused by the land [19], lower accuracy in the coastal and inland areas (see e.g., [14]).…”

Section: Advanced Altimeter Processing Methods -Retrackingmentioning

confidence: 99%

Radar Satellite Altimetry in Geodesy - Theory, Applications and Recent Developments

Grgić¹,

Bašić²

2021

Geodetic Sciences - Theory, Applications and Recent Developments

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Radar satellite altimetry has revolutionized our understanding of the Earth’s sea-level shape and its change over time, monitoring of the natural and human-induced water cycle, marine gravity computations, seafloor relief (bathymetry) reconstruction, tectonics, water mass balance change monitoring, etc., thus providing significant impact in geodesy. Today satellite radar altimetry is critical for unifying the vertical height systems, regional and global geoid modeling, monitoring of the sea level rise impact, monitoring of the ice sheet melting, and others. This chapter gives an overview of the technology itself and the recent developments including the SAR (Synthetic Aperture Radar) altimetry, coastal altimetry retracking methods, and new satellite missions (e.g. Sentinel-6). Besides, the chapter presents recent applied studies utilizing the altimeter data for ice sheet monitoring, vertical land motion estimating, bathymetric computations, and marine geoid modeling.

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Section: Advanced Altimeter Processing Methods -Retrackingmentioning

confidence: 99%

Radar Satellite Altimetry in Geodesy - Theory, Applications and Recent Developments

Grgić¹,

Bašić²

2021

Geodetic Sciences - Theory, Applications and Recent Developments

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“…Satellite altimetry has provided high-quality, global observations of sea surface height since early 1990s [4,5]. The altimeter data in this study are monthly gridded sea level anomaly maps at 0.25 • × 0.25 • spatial resolution with respect to a 20-year (1993-2012) mean sea level, which are provided by the Archiving, Validation, and Interpretation of Satellite Oceanographic (AVISO) data center (http://www.aviso.altimetry.fr/en/home.html, accessed on 19 January 2021), which are sea level anomaly products merged from several satellite altimetry missions of TOPEX/Poseidon, Jason-1/2, ERS-1/ERS-2, ENVISAT, GFO, Cryosat-2, Saral/AltiKa, and HY-2A.…”

Section: Satellite Altimetric Datamentioning

confidence: 99%

“…Since the early 1990s, satellite altimetry has provided near-global and high-quality observations of sea surface heights. Accuracy of satellite altimetric measurements is higher than 3 cm in open ocean, but rapidly decreases in marginal seas and when approaching coastal area [4,5]. This technique examines seasonal sea level cycle with high spatial coverage and resolution in coastal and open oceans.…”

Section: Introductionmentioning

confidence: 99%

Annual Sea Level Amplitude Analysis over the North Pacific Ocean Coast by Ensemble Empirical Mode Decomposition Method

Lan

Kuo

et al. 2021

Remote Sensing

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Understanding spatial and temporal changes of seasonal sea level cycles is important because of direct influence on coastal systems. The annual sea level cycle is substantially larger than semi-annual cycle in most parts of the ocean. Ensemble empirical mode decomposition (EEMD) method has been widely used to study tidal component, long-term sea level rise, and decadal sea level variation. In this work, EEMD is used to analyze the observed monthly sea level anomalies and detect annual cycle characteristics. Considering that the variations of the annual sea level variation in the Northeast Pacific Ocean are poorly studied, the trend and characteristics of annual sea level amplitudes and related mechanisms in the North Pacific Ocean are investigated using long-term tide gauge records covering 1950–2016. The average annual amplitude of coastal sea level exhibits interannual-to-decadal variability within the range of 14–220 mm. The largest value of ~174 mm is observed in the west coast of South China Sea. In the other coastal regions of North Pacific Ocean, the mean annual amplitude is relatively low between 77 and 124 mm for the western coast and 84 and 87 mm for the eastern coast. The estimated trend values for annual sea level amplitudes in the western coastal areas of South China Sea and Northeast Pacific Ocean have statistically decreased over 1952–2014 with a range of −0.77 mm·yr−1 to −0.11 mm·yr−1. Our results suggested that the decreasing annual amplitude in the west coast of South China Sea is in good agreement with the annual mean wind stress associated with the Pacific Decadal Oscillation (PDO). This wind phenomenon also explains the temporal variations of annual sea level amplitude in Northeast Pacific Ocean, especially the high correlations since 1980 (R = 0.61−0.72).

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“…However, coastal zones, which host the most in-situ sea level measurements, pose additional challenges. Firstly, altimeter waveforms from areas close to the coast often contain artifacts, mainly due to land contamination of the off-nadir satellite altimeter footprint [4] and the lower surface roughness of calm seas [5], which distort the altimeter waveform shape and cause unreliable retrievals of geophysical parameters [6]. Secondly, the corrections are less likely to capture the enhanced variability of the processes mentioned above over the coastal shelf [7]; some types of corrections (in particular, radiometer-or altimeter-based) degrade due to the presence of land in the instrument footprint [3].…”

Section: Introductionmentioning

confidence: 99%

The Impact of Altimetry Corrections of Sentinel-3A Sea Surface Height in the Coastal Zone of the Northwest Atlantic

2023

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Corrections to altimeter-measured sea surface height anomalies (SSHA) have a larger proportional effect for synthetic aperture radar (SAR) altimetry than conventional, pulse-limited altimetry because of lower range noise. Here, we quantified the impact of the current generation of altimeter corrections in the coastal zone of the Northwest Atlantic, a region with significant dynamic activity. In this study, we used the sea level variance analysis to determine the change in variance for the altimeter corrections—range, geophysical, and mean surface—compared to the baseline. We also evaluated the performance of two coastal retrackers, ALES (empirical) and SAMOSA++ (fully analytical), against the SSHA from the Radar Altimeter Database System (RADS), which uses the standard SAR retracker. Tide corrections caused the largest change in sea level variance, followed by wet tropospheric corrections and sea state bias. Most non-standard altimeter corrections failed to reduce the sea level variance and performed markedly worse closer to the coast. Coastal retrackers showed a higher deviation from the standard SSHA closer to the coast, especially when the backscatter coefficient was high and the significant wave height was low. We conclude that further development of coastal corrections is needed. Contrary to our prior expectation, we found that standard altimetry corrections appear to perform as well as alternative more advanced/tailored corrections.

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User Requirements in the Coastal Ocean for Satellite Altimetry

Cited by 8 publications

References 0 publications

Radar Satellite Altimetry in Geodesy - Theory, Applications and Recent Developments

Radar Satellite Altimetry in Geodesy - Theory, Applications and Recent Developments

Annual Sea Level Amplitude Analysis over the North Pacific Ocean Coast by Ensemble Empirical Mode Decomposition Method

The Impact of Altimetry Corrections of Sentinel-3A Sea Surface Height in the Coastal Zone of the Northwest Atlantic

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