Absolute Baltic Sea Level Trends in the Satellite Altimetry Era: A Revisit

Passaro, Marcello; Müller, Felix L.; Oelsmann, Julius; Rautiainen, Laura; Dettmering, D; Hart-Davis, Michael; Abulaitijiang, Adili; Andersen, Ole; Høyer, Jacob L.; Madsen, Kristine S.; Ringgaard, Ida Margrethe; Särkkä, Jani; Scarrott, Rory; Schwatke, C; Seitz, Florian; Tuomi, Laura; Restano, Marco; Benvéniste, Jérôme

doi:10.3389/fmars.2021.647607

Cited by 36 publications

(56 citation statements)

References 48 publications

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“…For missions using the REAPER and TOPEX retrackers, a coastal flag is implemented that restricts the use of SLA data up to 7 km from the coastline. For missions using the ALES retracker, however, this distance to the coast is decreased to 3 km (Passaro et al, 2021). An additional flag is also added limiting the absolute value of sea level anomalies to ± 2.5 m (Savcenko and Bosch, 2012).…”

Section: The Altimetry Sla Productmentioning

confidence: 99%

“…3.1 The global EOT20 model EOT20 presents global estimations of 17 tidal constituents with these tidal atlases being available from https://doi.org/10.17882/79489 (Hart-Davis et al, 2021). Global atlases of both ocean and load tides are provided, containing information about the amplitudes and phases as well as the real and imaginary components for all of the tidal constituents.…”

Section: Tide Model Assessment and Validationmentioning

confidence: 99%

“…The ocean and load tides from EOT20 are available at https://doi.org/10.17882/79489 (Hart-Davis et al, 2021). The GMT data used to create the land-sea mask can be found at http://gmt.soest.hawaii.edu (last access: 5 August 2021).…”

Section: Data Availabilitymentioning

confidence: 99%

“…The satellite altimetry data used in the model creation can be found at https://openadb.dgfi.tum.de/ (last access: 5 August 2021). The tide gauges from the TICON dataset used in the validation of the tide model are available at https://doi.org/10.1594/PANGAEA.896587 (Piccioni et al, 2018a).…”

Section: Data Availabilitymentioning

confidence: 99%

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EOT20: a global ocean tide model from multi-mission satellite altimetry

Hart-Davis¹,

Piccioni²,

Dettmering³

et al. 2021

Earth Syst. Sci. Data

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Abstract. EOT20 is the latest in a series of empirical ocean tide (EOT) models derived using residual tidal analysis of multi-mission satellite altimetry at DGFI-TUM. The amplitudes and phases of 17 tidal constituents are provided on a global 0.125∘ grid based on empirical analysis of seven satellite altimetry missions and four extended missions. The EOT20 model shows significant improvements compared to the previous iteration of the global model (EOT11a) throughout the ocean, particularly in the coastal and shelf regions, due to the inclusion of more recent satellite altimetry data as well as more missions, the use of the updated FES2014 tidal model as a reference to estimated residual signals, the inclusion of the ALES retracker and improved coastal representation. In the validation of EOT20 using tide gauges and ocean bottom pressure data, these improvements in the model compared to EOT11a are highlighted with the root sum square (RSS) of the eight major tidal constituents improving by ∼ 1.4 cm for the entire global ocean with the major improvement in RSS (∼ 2.2 cm) occurring in the coastal region. Concerning the other global ocean tidal models, EOT20 shows an improvement of ∼ 0.2 cm in RSS compared to the closest model (FES2014) in the global ocean. Variance reduction analysis was conducted comparing the results of EOT20 with FES2014 and EOT11a using the Jason-2, Jason-3 and SARAL satellite altimetry missions. From this analysis, EOT20 showed a variance reduction for all three satellite altimetry missions with the biggest improvement in variance occurring in the coastal region. These significant improvements, particularly in the coastal region, provide encouragement for the use of the EOT20 model as a tidal correction for satellite altimetry in sea-level research. All ocean and load tide data from the model can be freely accessed at https://doi.org/10.17882/79489 (Hart-Davis et al., 2021). The tide gauges from the TICON dataset used in the validation of the tide model, are available at https://doi.org/10.1594/PANGAEA.896587 (Piccioni et al., 2018a).

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Section: The Altimetry Sla Productmentioning

confidence: 99%

Section: Tide Model Assessment and Validationmentioning

confidence: 99%

Section: Data Availabilitymentioning

confidence: 99%

Section: Data Availabilitymentioning

confidence: 99%

See 2 more Smart Citations

EOT20: a global ocean tide model from multi-mission satellite altimetry

Hart-Davis¹,

Piccioni²,

Dettmering³

et al. 2021

Earth Syst. Sci. Data

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“…Investigations of global sea level from satellite altimetry have been done for almost three decades following the launch of the ERS-1 and TOPEX/Poseidon altimeters in the early 1990s. Since then, several additional altimeter missions have followed, allowing for the continued assessment of sea level trends both in the open ocean and in the coastal regions (e.g., [1][2][3]). However, errors resulting from ocean tide signals continue to affect the studying of sea surface processes using along-track altimetry.…”

Section: Introductionmentioning

confidence: 99%

Regional Evaluation of Minor Tidal Constituents for Improved Estimation of Ocean Tides

Hart-Davis¹,

Dettmering²,

Sulzbach

et al. 2021

Remote Sensing

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Satellite altimetry observations have provided a significant contribution to the understanding of global sea surface processes, particularly allowing for advances in the accuracy of ocean tide estimations. Currently, almost three decades of satellite altimetry are available which can be used to improve the understanding of ocean tides by allowing for the estimation of an increased number of minor tidal constituents. As ocean tide models continue to improve, especially in the coastal region, these minor tides become increasingly important. Generally, admittance theory is used by most global ocean tide models to infer several minor tides from the major tides when creating the tidal correction for satellite altimetry. In this paper, regional studies are conducted to compare the use of admittance theory to direct estimations of minor tides from the EOT20 model to identify which minor tides should be directly estimated and which should be inferred. The results of these two approaches are compared to two global tide models (TiME and FES2014) and in situ tide gauge observations. The analysis showed that of the eight tidal constituents studied, half should be inferred (2N2, ϵ2, MSF and T2), while the remaining four tides (J1, L2, μ2 and ν2) should be directly estimated to optimise the ocean tidal correction. Furthermore, for certain minor tides, the other two tide models produced better results than the EOT model, suggesting that improvements can be made to the tidal correction made by EOT when incorporating tides from the two other tide models. Following on from this, a new approach of merging tidal constituents from different tide models to produce the ocean tidal correction for satellite altimetry that benefits from the strengths of the respective models is presented. This analysis showed that the tidal correction created based on the recommendations of the tide gauge analysis provided the highest reduction of sea-level variance. Additionally, the combination of the EOT20 model with the minor tides of the TiME and FES2014 model did not significantly increase the sea-level variance. As several additional minor tidal constituents are available from the TiME model, this opens the door for further investigations into including these minor tides and optimising the tidal correction for improved studies of the sea surface from satellite altimetry and in other applications, such as gravity field modelling.

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On the potential of mapping sea level anomalies from satellite altimetry with Random Forest Regression

Passaro¹,

Marie-Christin²

2023

Ocean Dynamics

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The sea level observations from satellite altimetry are characterised by a sparse spatial and temporal coverage. For this reason, along-track data are routinely interpolated into daily grids. These grids are strongly smoothed in time and space and are generated using an optimal interpolation routine requiring several pre-processing steps and covariance characterisation. In this study, we assess the potential of Random Forest Regression to estimate daily sea level anomalies. Along-track sea level data from 2004 are used to build a training dataset whose predictors are the neighbouring observations. The validation is based on the comparison against daily averages from tide gauges. The generated dataset is on average 10% more correlated to the tide gauge records than the commonly used product from Copernicus. While the latter is more optimised for the detection of spatial mesoscales, we show how the methodology of this study has the potential to improve the characterisation of sea level variability.

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Absolute Baltic Sea Level Trends in the Satellite Altimetry Era: A Revisit

Cited by 36 publications

References 48 publications

EOT20: a global ocean tide model from multi-mission satellite altimetry

EOT20: a global ocean tide model from multi-mission satellite altimetry

Regional Evaluation of Minor Tidal Constituents for Improved Estimation of Ocean Tides

On the potential of mapping sea level anomalies from satellite altimetry with Random Forest Regression

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