Evaluation of SARAL/AltiKa performance using GNSS/IMU equipped buoy in Sajafi, Imam Hassan and Kangan Ports

Ardalan, Alireza A.; Jazireeyan, Iraj; Abdi, Naser; Rezvani, Mohammad-Hadi

doi:10.1016/j.asr.2018.01.001

Cited by 5 publications

(6 citation statements)

References 27 publications

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“…The comparison with a small surface side-cover radar with simultaneous observations yielded a tidal measurement accuracy of about 1 cm (RMSE of 1.12 cm) for the GNSS buoy, which is similar to that obtained from previous deployments of similarly structured GNSS buoys [34], and the remaining measurement error of 1 cm was related to the performance of the GNSS technology and receiver hardware. (2) The data from the four antennas mounted on the GNSS buoy were processed to obtain the attitude time series of the buoy (Figure 8), and it was found that the magnitude of the change in the attitude angle in the roll and pitch directions in the sea of the GNSS buoy maintained a high degree of consistency, which also verified the previous conclusions of the attitude measurements using the GNSS/INS method [21].…”

Section: Discussionsupporting

confidence: 75%

“…At present, the attitude measurement methods in the marine environment mainly include two kinds: inertial navigation technology and GNSS positioning technology [ 18 , 19 ]. Inertial Navigation Systems (INSs) with integrated gyroscopes and accelerometers provide highly accurate, high sampling rate acceleration and angular velocity information in a short period of time [ 20 , 21 ]. Scholars have already conducted experiments on board GNSS buoys [ 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

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Sea Surface Height Measurements Based on Multi-Antenna GNSS Buoys

Xue,

Yang,

Zhao

et al. 2024

Sensors

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Sea level monitoring is an essential foundational project for studying global climate change and the rise in sea levels. Satellite radar altimeters, which can sometimes provide inaccurate sea surface height data near the coast, are affected by both the instrument itself and geophysical factors. Buoys equipped with GNSS receivers offer a relatively flexible deployment at sea, allowing for long-term, high-precision measurements of sea surface heights. When operating at sea, GNSS buoys undergo complex movements with multiple degrees of freedom. Attitude measurements are a crucial source of information for understanding the motion state of the buoy at sea, which is related to the buoy’s stability and reliability during its development. In this study, we designed and deployed a four-antenna GNSS buoy with both position and attitude measurement capabilities near Jimiya Wharf in Qingdao, China, to conduct offshore sea surface monitoring activities. The GNSS data were processed using the Precise Point Positioning (PPK) method to obtain a time series of sea surface heights, and the accuracy was evaluated using synchronous observation data from a small sea surface height radar. The difference between the GNSS buoy and the full-time radar was calculated, resulting in a root-mean-square error (RMSE) of 1.15 cm. Concurrently, the attitude of the GNSS buoy was calculated using multi-antenna technology, and the vertical elevation of the GNSS buoy antenna was corrected using the obtained attitude data. The RMSE between the corrected GNSS buoy data and the high ground radar was 1.12 cm, indicating that the four-antenna GNSS buoy can not only acquire high-precision coastal sea level data but also achieve synchronous measurement of the buoy’s attitude. Furthermore, the data accuracy was also improved after the sea level attitude correction.

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Section: Discussionsupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Sea Surface Height Measurements Based on Multi-Antenna GNSS Buoys

Xue,

Yang,

Zhao

et al. 2024

Sensors

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“…The GIA-induced geoid change can be obtained from a suitable geoid change model that usually accompanies a GIA model (for the Baltic Sea region, the NKG2016LU VLM model provides geoid change). Concerning the current study, also bear in mind that GNSS-based techniques are a common approach for validating and calibrating satellite altimetry results [89][90][91]. Hence, consideration of the VLM occurring at the GNSS reference stations is necessary for consistent comparisons (cf.…”

Section: Discussionmentioning

confidence: 99%

Treatment of Tide Gauge Time Series and Marine GNSS Measurements for Vertical Land Motion with Relevance to the Implementation of the Baltic Sea Chart Datum 2000

et al. 2022

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Tide gauge (TG) time series and GNSS measurements have become standard datasets for various scientific and practical applications. However, the TG and geodetic networks in the Baltic Sea region are deforming due to vertical land motion (VLM), the primary cause of which is the glacial isostatic adjustment. Consequently, a correction for VLM, either obtained from a suitable VLM model or by utilizing space-geodetic techniques, must be applied to ensure compatibility of various data sources. It is common to consider the VLM rate relative to an arbitrary reference epoch, but this also yields that the resulting datasets may not be directly comparable. The common height reference, Baltic Sea Chart Datum 2000 (BSCD2000), has been initiated to facilitate the effective use of GNSS methods for accurate navigation and offshore surveying. The BSCD2000 agrees with the current national height realizations of the Baltic Sea countries. As TGs managed by national authorities are rigorously connected to the national height systems, the TG data can also be used in a common system. Hence, this contribution aims to review the treatment of TG time series for VLM and outline potential error sources for utilizing TG data relative to a common reference. Similar consideration is given for marine GNSS measurements that likewise require VLM correction for some marine applications (such as validating marine geoid models). The described principles are illustrated by analyzing and discussing numerical examples. These include investigations of TG time series and validation of shipborne GNSS determined sea surface heights. The latter employs a high-resolution geoid model and hydrodynamic model-based dynamic topography, which is linked to the height reference using VLM corrected TG data. Validation of the presented VLM corrected marine GNSS measurements yields a 1.7 cm standard deviation and –2.7 cm mean residual. The estimates are 1.9 cm and –10.2 cm, respectively, by neglecting VLM correction. The inclusion of VLM correction thus demonstrates significant improvement toward data consistency. Although the focus is on the Baltic Sea region, the principles described here are also applicable elsewhere.

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“…Various validation methods are able to determine the accuracy of altimetric heights. For instance, Etcheverry et al [12] used 478 global tide gauges to verify gridded altimetry sea-level anomaly (SLA) [12], while Ardalan et al [13] deployed Global Positioning System (GPS) buoys to evaluate SARAL/AltiKa products. Moreover, Birgiel et al [10] used the precise national geoid model to examine Sentinel-3 coastal product with a SAMOSA 2 retracker, and Bonnefond et al [14] used a GPS-catamaran for validation.…”

Section: Introductionmentioning

confidence: 99%

Validation of Copernicus Sea Level Altimetry Products in the Baltic Sea and Estonian Lakes

et al. 2020

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Multi-mission satellite altimetry (e.g., ERS, Envisat, TOPEX/Poseidon, Jason) data have enabled a synoptic-scale view of ocean variations in past decades. Since 2016, the Sentinel-3 mission has provided better spatial and temporal sampling compared to its predecessors. The Sentinel-3 Ku/C Radar Altimeter (SRAL) is one of the synthetic aperture radar altimeters (SAR Altimeter) which is more precise for coastal and lake observations. The article studies the performance of the Sentinel-3 Level-2 sea level altimetry products in the coastal areas of the Baltic Sea and on two lakes of Estonia. The Sentinel-3 data were compared with (i) collocated Global Navigation Satellite System (GNSS) ship measurements, (ii) the Estonian geoid model (EST-GEOID2017) together with sea-level anomaly corrections from the tide gauges, and (iii) collocated buoy measurements. The comparisons were carried out along seven Sentinel-3A/B tracks across the Baltic Sea and Estonian lakes in 2019. In addition, the Copernicus Marine Environment Monitoring Service (CMEMS) Level-3 sea-level products and the Nucleus for European Modelling of the Ocean (NEMO) reanalysis outcomes were compared with measurements from Estonia’s 21 tide gauges and the buoy deployed offshore. Our results showed that the uncertainty of the Sentinel-3 Level-2 altimetry product was below decimetre level for the seacoast and the selected lakes of Estonia. Results from CMEMS Level-3 altimetry products showed a correlation of 0.83 (RMSE 0.18 m) and 0.91 (RMSE 0.27 m) when compared against the tide gauge measurements and the NEMO model, respectively. The overall performance of the altimetry products was very good, except in the immediate vicinity of the coastline and for the lakes, where the accuracy was nearly three times lower than for the open sea, but still acceptably good.

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Evaluation of SARAL/AltiKa performance using GNSS/IMU equipped buoy in Sajafi, Imam Hassan and Kangan Ports

Cited by 5 publications

References 27 publications

Sea Surface Height Measurements Based on Multi-Antenna GNSS Buoys

Sea Surface Height Measurements Based on Multi-Antenna GNSS Buoys

Treatment of Tide Gauge Time Series and Marine GNSS Measurements for Vertical Land Motion with Relevance to the Implementation of the Baltic Sea Chart Datum 2000

Validation of Copernicus Sea Level Altimetry Products in the Baltic Sea and Estonian Lakes

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