The Sea State CCI dataset v1: towards a Sea State Climate Data
Record based on satellite observations

Dodet, Guillaume; Piollé, Jean-François; Quilfen, Yves; Abdalla, Saleh; Accensi, Mickaël; Ardhuin, Fabrice; Ash, Ellis; Bidlot, Jean‐Raymond; Gommenginger, Christine; Marechal, Gwendal; Passaro, Marcello; Quartly, Graham D.; Stopa, Justin E.; Timmermans, Ben; Young, Ian R.; Cipollini, Paolo; Donlon, Craig

doi:10.5194/essd-2019-253

Cited by 7 publications

(8 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One of the main objectives of the ESA SeaState_cci project is to produce a consistent climate-quality time-series of SWH estimates across different satellite missions, of which the data was recorded in the past 25 years [71].…”

Section: Selection and Decision Process Of Esa Seastate_cci Consortiummentioning

confidence: 99%

Round Robin Assessment of Radar Altimeter Low Resolution Mode and Delay-Doppler Retracking Algorithms for Significant Wave Height

et al. 2020

Self Cite

View full text Add to dashboard Cite

Radar altimeters have been measuring ocean significant wave height for more than three decades, with their data used to record the severity of storms, the mixing of surface waters and the potential threats to offshore structures and low-lying land, and to improve operational wave forecasting. Understanding climate change and long-term planning for enhanced storm and flooding hazards are imposing more stringent requirements on the robustness, precision, and accuracy of the estimates than have hitherto been needed. Taking advantage of novel retracking algorithms, particularly developed for the coastal zone, the present work aims at establishing an objective baseline processing chain for wave height retrieval that can be adapted to all satellite missions. In order to determine the best performing retracking algorithm for both Low Resolution Mode and Delay-Doppler altimetry, an objective assessment is conducted in the framework of the European Space Agency Sea State Climate Change Initiative project. All algorithms process the same Level-1 input dataset covering a time-period of up to two years. As a reference for validation, an ERA5-based hindcast wave model as well as an in-situ buoy dataset from the Copernicus Marine Environment Monitoring Service In Situ Thematic Centre database are used. Five different metrics are evaluated: percentage and types of outliers, level of measurement noise, wave spectral variability, comparison against wave models, and comparison against in-situ data. The metrics are evaluated as a function of the distance to the nearest coast and the sea state. The results of the assessment show that all novel retracking algorithms perform better in the majority of the metrics than the baseline algorithms currently used for operational generation of the products. Nevertheless, the performance of the retrackers strongly differ depending on the coastal proximity and the sea state. Some retrackers show high correlations with the wave models and in-situ data but significantly under- or overestimate large-scale spectral variability. We propose a weighting scheme to select the most suitable retrackers for the Sea State Climate Change Initiative programme.

show abstract

Section: Selection and Decision Process Of Esa Seastate_cci Consortiummentioning

confidence: 99%

Round Robin Assessment of Radar Altimeter Low Resolution Mode and Delay-Doppler Retracking Algorithms for Significant Wave Height

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…The CCI2019 dataset corresponds to CCI Sea State version 1.1 level 4 product developed within the European Space Agency Climate Change Initiative for Sea State (Piollé, Dodet & Quilfen, et al, ). The CCI2019 dataset is a multimission‐gridded (1°) product spanning 1992–2018 (Dodet et al, ). It extends the GlobWave dataset (1985–2016) up to 2018 by including more recent missions (JASON‐3, SARAL, and CRYOSAT‐2) but does not currently include GEOSAT nor SENTINEL‐3A.…”

Section: Sea State Datasetsmentioning

confidence: 99%

Global Wave Height Trends and Variability from New Multimission Satellite Altimeter Products, Reanalyses, and Wave Buoys

Timmermans

Gommenginger

Dodet

et al. 2020

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

Long-term changes in ocean surface waves are relevant to society and climate research.Significant wave height climatologies and trends over 1992-2017 are intercompared in four recent high-quality global datasets using a consistent methodology. For two products based on satellite altimetry, including one from the European Space Agency Climate Change Initiative for Sea State, regional differences in mean climatology are linked to low and high sea states. Trends from the altimetry products, and two reanalysis and hindcast datasets, show general similarity in spatial variation and magnitude but with major differences in equatorial regions and the Indian Ocean. Discrepancies between altimetry products likely arise from differences in calibration and quality control. However, multidecadal observations at two buoy stations also highlight issues with wave buoy data, raising questions about their unqualified use, and more fundamentally about uncertainty in all products.Plain Language Summary Changes to ocean waves over decades and longer are of considerable importance to the climate, the society, and the marine economy. Accurate observations of waves spanning many decades are required to understand long-term changes, but the challenges and cost of measuring waves worldwide with devices like buoys means that alternatives like Earth-orbiting satellites become attractive. We compare two recently published global wave products derived from the same satellite observations, with two high-quality products from computer simulations and buoy measurements. Using a consistent methodology, we find important differences between the satellite products, and the simulations, in the reported average global wave conditions, and their evolution in time. The disagreement between the satellite products points to complex differences in the way satellite data are corrected, which raises questions about uncertainty in these products, and more generally, about what is our most reliable long-term observational record of sea state.

show abstract

“…Figure 18f shows the corresponding scatter plot, revealing that, compared with Jason-3, the PLRM data on average deliver slightly lower values in low SWH regions and larger values in high SWH regions. Understanding these slight differences between different altimetric datasets is crucial when aiming to construct a homogeneous dataset across multiple missions [31].…”

Section: Consistency With Other Altimetry Datasetsmentioning

confidence: 99%

The Roles of the S3MPC: Monitoring, Validation and Evolution of Sentinel-3 Altimetry Observations

et al. 2020

Self Cite

View full text Add to dashboard Cite

The Sentinel-3 Mission Performance Centre (S3MPC) is tasked by the European Space Agency (ESA) to monitor the health of the Copernicus Sentinel-3 satellites and ensure a high data quality to the users. This paper deals exclusively with the effort devoted to the altimeter and microwave radiometer, both components of the Surface Topography Mission (STM). The altimeters on Sentinel-3A and -3B are the first to operate in delay-Doppler or SAR mode over all Earth surfaces, which enables better spatial resolution of the signal in the along-track direction and improved noise reduction through multi-looking, whilst the radiometer is a two-channel nadir-viewing system. There are regular routine assessments of the instruments through investigation of telemetered housekeeping data, calibrations over selected sites and comparisons of geophysical retrievals with models, in situ data and other satellite systems. These are performed both to monitor the daily production, assessing the uncertainties and errors on the estimates, and also to characterize the long-term performance for climate science applications. This is critical because an undetected drift in performance could be misconstrued as a climate variation. As the data are used by the Copernicus Services (e.g., CMEMS, Global Land Monitoring Services) and by the research community over open ocean, coastal waters, sea ice, land ice, rivers and lakes, the validation activities encompass all these domains, with regular reports openly available. The S3MPC is also in charge of preparing improvements to the processing, and of the development and tuning of algorithms to improve their accuracy. This paper is thus the first refereed publication to bring together the analysis of SAR altimetry across all these different domains to highlight the benefits and existing challenges.

show abstract

The Sea State CCI dataset v1: towards a Sea State Climate Data Record based on satellite observations

Cited by 7 publications

References 38 publications

Round Robin Assessment of Radar Altimeter Low Resolution Mode and Delay-Doppler Retracking Algorithms for Significant Wave Height

Round Robin Assessment of Radar Altimeter Low Resolution Mode and Delay-Doppler Retracking Algorithms for Significant Wave Height

Global Wave Height Trends and Variability from New Multimission Satellite Altimeter Products, Reanalyses, and Wave Buoys

The Roles of the S3MPC: Monitoring, Validation and Evolution of Sentinel-3 Altimetry Observations

Contact Info

Product

Resources

About