Accuracy assessment of global ocean tide models in the South China Sea using satellite altimeter and tide gauge data

2020 ◽  
Author(s):  
Yanguang Fu ◽  
Yikai Feng ◽  
Dongxu Zhou ◽  
Xinghua Zhou ◽  
Jie Li ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Tide Gauge ◽  
Accuracy Assessment ◽  
Global Ocean ◽  
Ocean Tide ◽  
Tide Gauge Data ◽  
Satellite Altimeter ◽  
Gauge Data ◽  
Ocean Tide Models

scholarly journals A 10-Year Comparison of Water Levels Measured with a Geodetic GPS Receiver versus a Conventional Tide Gauge

2017 ◽  
Vol 34 (2) ◽  
pp. 295-307 ◽  
Author(s):  
Kristine M. Larson ◽  
Richard D. Ray ◽  
Simon D. P. Williams
Keyword(s):  
Tide Gauge ◽  
Signal Propagation ◽  
Propagation Delay ◽  
Terrestrial Reference Frame ◽  
Water Levels ◽  
Sea Surface ◽  
Ocean Tide ◽  
Gps Receiver ◽  
Tide Gauge Data ◽  
Gauge Data

AbstractA standard geodetic GPS receiver and a conventional Aquatrak tide gauge, collocated at Friday Harbor, Washington, are used to assess the quality of 10 years of water levels estimated from GPS sea surface reflections. The GPS results are improved by accounting for (tidal) motion of the reflecting sea surface and for signal propagation delay by the troposphere. The RMS error of individual GPS water level estimates is about 12 cm. Lower water levels are measured slightly more accurately than higher water levels. Forming daily mean sea levels reduces the RMS difference with the tide gauge data to approximately 2 cm. For monthly means, the RMS difference is 1.3 cm. The GPS elevations, of course, can be automatically placed into a well-defined terrestrial reference frame. Ocean tide coefficients, determined from both the GPS and tide gauge data, are in good agreement, with absolute differences below 1 cm for all constituents save K1 and S1. The latter constituent is especially anomalous, probably owing to daily temperature-induced errors in the Aquatrak tide gauge.

scholarly journals Analysis of Upwelling Events in the Southern South China Sea Using Multi-Mission Satellite Altimeter

2021 ◽  
Vol 16 ◽  
pp. 1-15
Author(s):  
Ami Hassan Md Din ◽  
Abdul Rafiq Dolhan ◽  
Mohammad Hanif Hamden ◽  
Mat Nizam Uti ◽  
Muhammad Faiz Pa’suya
Keyword(s):  
South China Sea ◽  
South China ◽  
Tide Gauge ◽  
Ocean Current ◽  
Observation System ◽  
In Situ Observation ◽  
Limited Information ◽  
Satellite Altimeter ◽  
China Sea ◽  
Mission Satellite

Upwelling is a vital ocean behaviour, especially for the Fisheries Industry, where upwelling will help to detect fish ground at a particular ocean area. However, the study of upwelling is minimal and not well understood due to some reasons and constraints, such as limited observation. Upwelling lacks a comprehensive in-situ observation system where it relies on limited information collected from the ground-truthing execution such as ships, buoys, and current meter.  This study aims to analyse the upwelling pattern in the southern region of the South China Sea by using a multi-mission satellite altimeter. In order to derive the physical oceanography that involves upwelling, such as sea surface height (SSH), Mean Dynamic Topography (MDT), and the Sea Level Anomaly (SLA), the Radar Altimeter Database System is used. Five Satellite Altimeter mission is used in this study, which is JASON-2, JASON-3, CYROSAT2, SARAL, SENTINAL3A from 2013 to 2017. Validation is made using a statistical method showing a good correlation between Altimetry data and Tidal Data at tide gauge, which is 0.84 to 0.97, respectively. Also, monthly altimetry derived Geostrophic Current was assessed by analysing the current pattern where it shows a similarity with a previous study where the current velocity is 0.5ms-1 to 2ms-1. From the result, eddies can be seen in the seasonal and monthly Absolute Geostrophic Ocean Current (AGOC) map, indicating the present presence of upwelling. In conclusion, this study will benefit other researchers in terms of both upwelling and eddy studies. 

scholarly journals The nodal dependence of long-period ocean tides in the Drake Passage

2018 ◽  
Author(s):  
Philip L. Woodworth ◽  
Angela Hibbert
Keyword(s):  
Tide Gauge ◽  
Drake Passage ◽  
Ocean Tide ◽  
Phase Lag ◽  
Tide Gauge Data ◽  
Long Period ◽  
The North ◽  
Ocean Tide Model ◽  
Gauge Data ◽  
Tidal Variability

Abstract. Almost three decades of bottom pressure recorder (BPR) measurements at the Drake Passage, and 31 years of hourly tide gauge data from Vernadsky station on the Antarctic Peninsula, have been used to investigate the temporal and spatial variations in this region of the three main long-period tides Mf, Mm and Mt (in order of decreasing amplitude, with periods of a fortnight, a month and third of a month respectively). The amplitudes of Mf and Mt, and the phase lags for all three constituents, vary over the nodal cycle (18.61 years) in essentially the same way as in the equilibrium tide, so confirming the validity of Doodson's nodal factors for these constituents. The amplitude of Mm is found to be essentially constant, and so inconsistent at the three-sigma level from the ±13 % (or ~ ±0.15 mbar) anticipated variation over the nodal cycle, which can probably be explained by energetic non-tidal variability in the records at monthly timescales and longer. The north-south differences in amplitude for all three constituents are consistent with those in a modern ocean tide model (FES2014), as are those in phase lag for Mf and Mt, while the difference for Mm is smaller than in the model. BPR measurements are shown to be superior to conventional tide gauge data in such tidal studies, thanks to the lower proportion of non-tidal variability in the records.

scholarly journals ACCURACY ASSESSMENT OF RECENT GLOBAL OCEAN TIDE MODELS AROUND ANTARCTICA

2017 ◽  
Vol XLII-2/W7 ◽  
pp. 1521-1528 ◽  
Author(s):  
J. Lei ◽  
F. Li ◽  
S. Zhang ◽  
H. Ke ◽  
Q. Zhang ◽  
...  
Keyword(s):  
Accuracy Assessment ◽  
Weddell Sea ◽  
Global Ocean ◽  
Ocean Tide ◽  
Polar Regions ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Ross Ice Shelf ◽  
Shelf Region ◽  
Ocean Tide Models

Due to the coverage limitation of T/P-series altimeters, the lack of bathymetric data under large ice shelves, and the inaccurate definitions of coastlines and grounding lines, the accuracy of ocean tide models around Antarctica is poorer than those in deep oceans. Using tidal measurements from tide gauges, gravimetric data and GPS records, the accuracy of seven state-of-the-art global ocean tide models (DTU10, EOT11a, GOT4.8, FES2012, FES2014, HAMTIDE12, TPXO8) is assessed, as well as the most widely-used conventional model FES2004. Four regions (Antarctic Peninsula region, Amery ice shelf region, Filchner-Ronne ice shelf region and Ross ice shelf region) are separately reported. The standard deviations of eight main constituents between the selected models are large in polar regions, especially under the big ice shelves, suggesting that the uncertainty in these regions remain large. Comparisons with in situ tidal measurements show that the most accurate model is TPXO8, and all models show worst performance in Weddell sea and Filchner-Ronne ice shelf regions. The accuracy of tidal predictions around Antarctica is gradually improving.

scholarly journals Reconstruction and Projection of Sea Level Around the Korean Peninsula Using Cyclostationary Empirical Orthogonal Functions

2017 ◽  
Author(s):  
Se-Hyeon Cheon ◽  
Benjamin D. Hamlington ◽  
Kyung-Duck Suh
Keyword(s):  
Sea Level ◽  
Satellite Data ◽  
Korean Peninsula ◽  
Tide Gauge ◽  
Tide Gauges ◽  
Tide Gauge Data ◽  
Satellite Altimeter ◽  
Reconstruction Process ◽  
The Past ◽  
Gauge Data

Abstract. Since the advent of the modern satellite altimeter era, the understanding of the sea level has increased dramatically. The satellite altimeter record, however, dates back only to the 1990s. The tide gauge record, on the other hand, extends through the 20th century, but with poor spatial coverage when compared to the satellites. Many studies have been conducted to extend the spatial resolution of the satellite data into the past by finding novel ways to combine the satellite data and tide gauge data in what are known as sea level reconstructions. However, most of the reconstructions of sea level were conducted on a global scale, leading to reduced accuracy on regional levels, particularly where there are relatively few tide gauges. The sea around the Korean Peninsula is one such area with few tide gauges prior to 1960. In this study, new methods are proposed to reconstruct the past sea level and project the future sea level around the Korean Peninsula. Using spatial patterns obtained from a cyclo-stationary empirical orthogonal function decomposition of satellite data, we reconstruct sea level over the time period from 1900 to 2014. Sea surface temperature data and altimeter data are used simultaneously in the reconstruction process, leading to an elimination of reliance on tide gauge data. Although the tide gauge data was not used in the reconstruction process, the reconstructed results showed better agreement with the tide gauge observations in the region than previous studies that incorporated the TG data. This study demonstrates a reconstruction technique that can be used on regional levels, with particular emphasis on areas with poor tide gauge coverage.

scholarly journals Reconstruction of sea level around the Korean Peninsula using cyclostationary empirical orthogonal functions

Ocean Science ◽  
2018 ◽  
Vol 14 (5) ◽  
pp. 959-970 ◽  
Author(s):  
Se-Hyeon Cheon ◽  
Benjamin D. Hamlington ◽  
Kyung-Duck Suh
Keyword(s):  
Sea Level ◽  
Satellite Data ◽  
Korean Peninsula ◽  
Tide Gauge ◽  
Tide Gauges ◽  
Tide Gauge Data ◽  
Satellite Altimeter ◽  
Reconstruction Process ◽  
Spatial Coverage ◽  
Gauge Data

Abstract. Since the advent of the modern satellite altimeter era, the understanding of the sea level has increased dramatically. The satellite altimeter record, however, dates back only to the 1990s. The tide gauge record, on the other hand, extends through the 20th century but with poor spatial coverage when compared to the satellites. Many studies have been conducted to create a dataset with the spatial coverage of the satellite datasets and the temporal length of the tide gauge records by finding novel ways to combine the satellite data and tide gauge data in what is known as sea level reconstruction. However, most of the reconstructions of sea level were conducted on a global scale, leading to reduced accuracy on regional levels, especially when there are relatively few tide gauges. The seas around the Korean Peninsula are one such area with few tide gauges before 1960. In this study, new methods are proposed to reconstruct past sea level around the Korean Peninsula. Using spatial patterns obtained from a cyclostationary empirical orthogonal function decomposition of satellite data, we reconstruct sea level over the period from 1900 to 2014. Sea surface temperature data and altimeter data are used simultaneously in the reconstruction process, leading to an elimination of reliance on tide gauge data. Although we did not use the tide gauge data in the reconstruction process, the reconstructed sea level has a better agreement with the tide gauge observations in the region than previous studies that incorporated the tide gauge data. This study demonstrates a reconstruction technique that can potentially be used at regional levels, with particular emphasis on areas with poor tide gauge coverage.

scholarly journals The nodal dependence of long-period ocean tides in the Drake Passage

Ocean Science ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 711-730 ◽  
Author(s):  
Philip L. Woodworth ◽  
Angela Hibbert
Keyword(s):  
Tide Gauge ◽  
Drake Passage ◽  
Ocean Tide ◽  
Phase Lag ◽  
Tide Gauge Data ◽  
Tide Gauge Records ◽  
Long Period ◽  
Ocean Tide Model ◽  
Gauge Data ◽  
Tidal Variability

Abstract. Almost three decades of bottom pressure recorder (BPR) measurements at the Drake Passage, and 31 years of hourly tide gauge data from the Vernadsky Research Base on the Antarctic Peninsula, have been used to investigate the temporal and spatial variations in this region of the three main long-period tides Mf, Mm and Mt (in order of decreasing amplitude, with periods of a fortnight, a month and one-third of a month, respectively). The amplitudes of Mf and Mt, and the phase lags for all three constituents, vary over the nodal cycle (18.61 years) in essentially the same way as in the equilibrium tide, so confirming the validity of Doodson's “nodal factors” for these constituents. The amplitude of Mm is found to be essentially constant, and so inconsistent at the 3σ level from the ±13 % (or ∼±0.15 mbar) anticipated variation over the nodal cycle, which can probably be explained by energetic non-tidal variability in the records at monthly timescales and longer. The north–south differences in amplitude for all three constituents are consistent with those in a modern ocean tide model (FES2014), as are those in phase lag for Mf and Mt, while the phase difference for Mm is smaller than in the model. BPR measurements are shown to be considerably superior to coastal tide gauge data in such studies, due to the larger proportion of non-tidal variability in the latter. However, correction of the tide gauge records for non-tidal variability results in the uncertainties in nodal parameters being reduced by a factor of 2 (for Mf at least) to a magnitude comparable (approximately twice) to those obtained from the BPR data.

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

2021 ◽  
Vol 13 (16) ◽  
pp. 3310
Author(s):  
Michael G. Hart-Davis ◽  
Denise Dettmering ◽  
Roman Sulzbach ◽  
Maik Thomas ◽  
Christian Schwatke ◽  
...  
Keyword(s):  
Sea Level ◽  
Satellite Altimetry ◽  
Tide Gauge ◽  
Sea Surface ◽  
Global Ocean ◽  
Ocean Tide ◽  
Ocean Tides ◽  
Tidal Constituents ◽  
Ocean Tide Models ◽  
Tidal Correction

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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