To address the problem of low quality of the outlier detection results caused by the irregular spatial distribution of crowdsourced bathymetric data, an intelligently optimized 3D-DBSCAN method is ...
{"title":"Detecting outliers in crowdsourced bathymetric data based on intelligently optimized 3D-DBSCAN algorithm","authors":"Shuaidong Jia, Hao Yuan, Lihua Zhang, Zhicheng Liang, Zhou Yinfei","doi":"10.1080/01490419.2023.2279086","DOIUrl":"https://doi.org/10.1080/01490419.2023.2279086","url":null,"abstract":"To address the problem of low quality of the outlier detection results caused by the irregular spatial distribution of crowdsourced bathymetric data, an intelligently optimized 3D-DBSCAN method is ...","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"27 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138516833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
AbstractInvestigating the global sea level budget is essential to quantify the total sea level change (altimetry) and its components, including the steric sea level change and the ocean mass change (gravity), where the latter is mainly attributed to four mass-driven components (Greenland, Antarctica, glaciers and land water storage). In this study, a 24-year global ocean mass change is derived by the joint use of Tongji-LEO2021 and Tongji-Grace2018 monthly gravity field models over 1993–2016, with which the sea level budgets in terms of rate and acceleration are investigated over global oceans within the latitudes 66oN to 66oS together with the IGG-SLR-HYBRID gravity field models, altimetry, steric and four mass-driven components. The statistical results show that the global mean ocean mass change rate accounts for ∼54% of 2.85 ± 0.30 mm/year of global mean total sea level change. The accelerations of global mean total sea level change and its components are 0.145 ± 0.025 mm/year2 (altimetry), 0.003 ± 0.021 mm/year2 (steric), 0.139 ± 0.047 mm/year2 (ocean mass from Tongji), and 0.137 ± 0.010 mm/year2 (the sum of mass-driven components) respectively, indicating that the global sea level budget in terms of acceleration can be closed and nearly no acceleration exists in the global mean steric sea level change for the period 1993–2016.Keywords: Global sea level changeGravity field modelsAltimetryStericAcceleration Disclosure StatementNo potential conflict of interest was reported by the author(s).Data Availability StatementThe merged altimetry gridded global sea level height anomalies are accessed at https://doi.org/10.24381/cds.4c328c78. The two situ steric datasets (EN4 and IK09) are accessed at https://doi.org/10.4121/12764933.v3. The Tongji-LEO2021 and Tongji-Grace2018 models are free to access from the websites of http://icgem.gfz-potsdam.de/series/03_other/Tongji/Tongji-LEO2021 and http://icgem.gfz-potsdam.de/series/03_other/Tongji/Tongji-Grace2018, respectively. Four mass components (i.e. Greenland, Antarctica, glaciers and land water storage) are accessed from https://catalogue.ceda.ac.uk/uuid/17c2ce31784048de93996275ee976fff. Besides, the IMBIE 2018 Antarctic and IMBIE 2019 Greenland datasets can be directly downloaded from the website of http://imbie.org/data-downloads/.Additional informationFundingThe research is supported by the Natural Science Foundation of China [42061134010, 42192532, 41731069 and 42174099] and the National Key R&D Program of China [2021YFB3900101].
{"title":"Global Sea Level Change Rate, Acceleration and Its Components from 1993 to 2016","authors":"Fengwei Wang, Yunzhong Shen, Qiujie Chen, Jianhua Chen, Jianhua Geng","doi":"10.1080/01490419.2023.2276478","DOIUrl":"https://doi.org/10.1080/01490419.2023.2276478","url":null,"abstract":"AbstractInvestigating the global sea level budget is essential to quantify the total sea level change (altimetry) and its components, including the steric sea level change and the ocean mass change (gravity), where the latter is mainly attributed to four mass-driven components (Greenland, Antarctica, glaciers and land water storage). In this study, a 24-year global ocean mass change is derived by the joint use of Tongji-LEO2021 and Tongji-Grace2018 monthly gravity field models over 1993–2016, with which the sea level budgets in terms of rate and acceleration are investigated over global oceans within the latitudes 66oN to 66oS together with the IGG-SLR-HYBRID gravity field models, altimetry, steric and four mass-driven components. The statistical results show that the global mean ocean mass change rate accounts for ∼54% of 2.85 ± 0.30 mm/year of global mean total sea level change. The accelerations of global mean total sea level change and its components are 0.145 ± 0.025 mm/year2 (altimetry), 0.003 ± 0.021 mm/year2 (steric), 0.139 ± 0.047 mm/year2 (ocean mass from Tongji), and 0.137 ± 0.010 mm/year2 (the sum of mass-driven components) respectively, indicating that the global sea level budget in terms of acceleration can be closed and nearly no acceleration exists in the global mean steric sea level change for the period 1993–2016.Keywords: Global sea level changeGravity field modelsAltimetryStericAcceleration Disclosure StatementNo potential conflict of interest was reported by the author(s).Data Availability StatementThe merged altimetry gridded global sea level height anomalies are accessed at https://doi.org/10.24381/cds.4c328c78. The two situ steric datasets (EN4 and IK09) are accessed at https://doi.org/10.4121/12764933.v3. The Tongji-LEO2021 and Tongji-Grace2018 models are free to access from the websites of http://icgem.gfz-potsdam.de/series/03_other/Tongji/Tongji-LEO2021 and http://icgem.gfz-potsdam.de/series/03_other/Tongji/Tongji-Grace2018, respectively. Four mass components (i.e. Greenland, Antarctica, glaciers and land water storage) are accessed from https://catalogue.ceda.ac.uk/uuid/17c2ce31784048de93996275ee976fff. Besides, the IMBIE 2018 Antarctic and IMBIE 2019 Greenland datasets can be directly downloaded from the website of http://imbie.org/data-downloads/.Additional informationFundingThe research is supported by the Natural Science Foundation of China [42061134010, 42192532, 41731069 and 42174099] and the National Key R&D Program of China [2021YFB3900101].","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"54 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135819421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
AbstractTo address the problem that the parameters are relatively fixed in the existing automatic methods of depth contour generalization, a case-based reasoning method for generalizing depth contours is proposed considering navigational safety and line shape. First, the structured description of depth contours before and after cartography generalization is made to form case samples. Then, driven by the training samples, the machine learning of BP neural network model is constructed, to obtain the simplification degree taking into consideration the preservation of contour shapes. Finally, the generalization parameters are flexibly adjusted based on the simplification degree obtained through the case-based reasoning, so that depth contours can be adaptively generalized for various complex situations. The experimental results demonstrate that: (1) The case-based reasoning method can make the generalization of depth contours comply with the principle of navigational safety; (2) The case-based reasoning method has a stronger applicability maintaining the shape of depth contour, and is more suitable for the automatic generalization of depth contours, compared with the rolling circle method and the triangulation method. Generally, the case-based reasoning method has the potential to improve cartographic quality meeting the requirements of IHO specification, supporting the automatic production of ENC and nautical chart product.Keywords: Chart generalizationdepth contour generalizationnavigational safety assuranceline shape preservationcase-based reasoning AcknowledgmentsWe would like to thank the editor and anonymous reviewers for their valuable suggestions. We have made some modifications according their suggestions.Disclosure statementNo potential conflict of interest was reported by the authors.This paper is supported by National Natural Science Foundation of China (41901320, 41871369).Additional informationFundingThis paper is supported by National Natural Science Foundation of China (41901320, 41871369).
{"title":"A Case-Based Reasoning Method for Generalizing Depth Contours considering Both Navigational Safety Assurance and Line Shape Preservation","authors":"Shuaidong Jia, Zikang Song, Lihua Zhang, Zhicheng Liang","doi":"10.1080/01490419.2023.2263907","DOIUrl":"https://doi.org/10.1080/01490419.2023.2263907","url":null,"abstract":"AbstractTo address the problem that the parameters are relatively fixed in the existing automatic methods of depth contour generalization, a case-based reasoning method for generalizing depth contours is proposed considering navigational safety and line shape. First, the structured description of depth contours before and after cartography generalization is made to form case samples. Then, driven by the training samples, the machine learning of BP neural network model is constructed, to obtain the simplification degree taking into consideration the preservation of contour shapes. Finally, the generalization parameters are flexibly adjusted based on the simplification degree obtained through the case-based reasoning, so that depth contours can be adaptively generalized for various complex situations. The experimental results demonstrate that: (1) The case-based reasoning method can make the generalization of depth contours comply with the principle of navigational safety; (2) The case-based reasoning method has a stronger applicability maintaining the shape of depth contour, and is more suitable for the automatic generalization of depth contours, compared with the rolling circle method and the triangulation method. Generally, the case-based reasoning method has the potential to improve cartographic quality meeting the requirements of IHO specification, supporting the automatic production of ENC and nautical chart product.Keywords: Chart generalizationdepth contour generalizationnavigational safety assuranceline shape preservationcase-based reasoning AcknowledgmentsWe would like to thank the editor and anonymous reviewers for their valuable suggestions. We have made some modifications according their suggestions.Disclosure statementNo potential conflict of interest was reported by the authors.This paper is supported by National Natural Science Foundation of China (41901320, 41871369).Additional informationFundingThis paper is supported by National Natural Science Foundation of China (41901320, 41871369).","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136033326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-25DOI: 10.1080/01490419.2023.2249229
Bimalkumar Patel, Apurva Prajapati, R. Sarangi, Bhargav Devliya, Hitesh Patel
Abstract TSM (Total suspended matter) is important metric because it influences ocean biogeochemistry and seaweed habitat. Light penetration is influenced by the TSM range, which is linked to primary producer photosynthesis. Many regional and global approaches for measuring various ocean parameters using satellite remote sensing have been developed. The authors developed the linear TSM algorithm in 2022 using in situ data from the Arabian Sea, which has been validated in this work utilising in situ sampling along the Bay of Bengal coast to test its resilience. The algorithm has the remote sensing reflectance band ratio Rrs681/Rrs490 that has been validated against in situ TSM (R2 = 0.88, MAD = 12.28, RMSE = 12.45, NRMSE = 11.60) and satellite validation with OLCI-A (Ocean and Land Colour Instrument-A). OLCI A TSM product discovered poor regression with in situ datasets, suggesting that the algorithm in OLCI A might be modified. The article infers that the validated TSM algorithm in the Bay of Bengal could be useful for different satellite-based synoptic TSM mapping for the Indian Oceansat-3 OCM (Ocean Colour Monitor) mission as TSM could benefit seaweeds and biogeochemistry by improving nutrient flow, trophic interactions, shielding against UV radiation, and adding organic carbon pool.
{"title":"Validation of the Total Suspended Matter (TSM) algorithm using in situ datasets over the Bay of Bengal Coastal Water","authors":"Bimalkumar Patel, Apurva Prajapati, R. Sarangi, Bhargav Devliya, Hitesh Patel","doi":"10.1080/01490419.2023.2249229","DOIUrl":"https://doi.org/10.1080/01490419.2023.2249229","url":null,"abstract":"Abstract TSM (Total suspended matter) is important metric because it influences ocean biogeochemistry and seaweed habitat. Light penetration is influenced by the TSM range, which is linked to primary producer photosynthesis. Many regional and global approaches for measuring various ocean parameters using satellite remote sensing have been developed. The authors developed the linear TSM algorithm in 2022 using in situ data from the Arabian Sea, which has been validated in this work utilising in situ sampling along the Bay of Bengal coast to test its resilience. The algorithm has the remote sensing reflectance band ratio Rrs681/Rrs490 that has been validated against in situ TSM (R2 = 0.88, MAD = 12.28, RMSE = 12.45, NRMSE = 11.60) and satellite validation with OLCI-A (Ocean and Land Colour Instrument-A). OLCI A TSM product discovered poor regression with in situ datasets, suggesting that the algorithm in OLCI A might be modified. The article infers that the validated TSM algorithm in the Bay of Bengal could be useful for different satellite-based synoptic TSM mapping for the Indian Oceansat-3 OCM (Ocean Colour Monitor) mission as TSM could benefit seaweeds and biogeochemistry by improving nutrient flow, trophic interactions, shielding against UV radiation, and adding organic carbon pool.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44232032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-08DOI: 10.1080/01490419.2023.2241636
Yinfei Zho, Lihua Zhang, Shuaidong Jia, Zeyuan Dai, Junnan Liu
Abstract Efficient collision avoidance (CA) route planning is one of the important technologies for ensuring the safety of autonomous ships. Many CA route planning studies have been developed for the open sea, but few studies have been conducted for ships in complex navigation environments. A complex navigation environment refers to water encompassing various factors, such as multiple obstacles, varying water depths, ships collision risk, and other maritime challenges. These factors collectively contribute to the complexity of the environment. CA planning in this type of environment is a special type of route planning. To address CA in complex navigation environments, firstly, the route binary tree algorithm is utilized for conducting global route planning in order to determine the optimal path. Secondly, this paper proposes a dynamic generation of local collision avoidance trajectories along the optimal path, seamlessly integrating global route optimization and local collision avoidance. Finally, a comparative analysis is conducted using classical techniques to verify the effectiveness of the proposed method. Numerical simulation results reveal that when a ship is taken as the object of CA in the open sea, the route generated using the proposed method exhibits a remarkable level of unity with the one generated by the benchmark method of improved Artificial Potential Field (APF), particularly in terms of collision avoidance strategy selection, collision avoidance trends, and the actual trajectory. The former’s computational efficiency is improved by at least 30%. When dealing with CA at sea, with complex navigation obstacles, the proposed method considers static complex navigation obstacles, dynamic ships, and their unpredictable strategies to timeously generate a safe path which considers some key rules from the COLREGS (International Regulations for Preventing Collisions at Sea) (IMO, 1972).
{"title":"Automatic Collision Avoidance Route Planning Method in Complex Navigation Environments","authors":"Yinfei Zho, Lihua Zhang, Shuaidong Jia, Zeyuan Dai, Junnan Liu","doi":"10.1080/01490419.2023.2241636","DOIUrl":"https://doi.org/10.1080/01490419.2023.2241636","url":null,"abstract":"Abstract Efficient collision avoidance (CA) route planning is one of the important technologies for ensuring the safety of autonomous ships. Many CA route planning studies have been developed for the open sea, but few studies have been conducted for ships in complex navigation environments. A complex navigation environment refers to water encompassing various factors, such as multiple obstacles, varying water depths, ships collision risk, and other maritime challenges. These factors collectively contribute to the complexity of the environment. CA planning in this type of environment is a special type of route planning. To address CA in complex navigation environments, firstly, the route binary tree algorithm is utilized for conducting global route planning in order to determine the optimal path. Secondly, this paper proposes a dynamic generation of local collision avoidance trajectories along the optimal path, seamlessly integrating global route optimization and local collision avoidance. Finally, a comparative analysis is conducted using classical techniques to verify the effectiveness of the proposed method. Numerical simulation results reveal that when a ship is taken as the object of CA in the open sea, the route generated using the proposed method exhibits a remarkable level of unity with the one generated by the benchmark method of improved Artificial Potential Field (APF), particularly in terms of collision avoidance strategy selection, collision avoidance trends, and the actual trajectory. The former’s computational efficiency is improved by at least 30%. When dealing with CA at sea, with complex navigation obstacles, the proposed method considers static complex navigation obstacles, dynamic ships, and their unpredictable strategies to timeously generate a safe path which considers some key rules from the COLREGS (International Regulations for Preventing Collisions at Sea) (IMO, 1972).","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47613952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-19DOI: 10.1080/01490419.2023.2232107
Gang Ma, T. Jin, Pengyuan Jiang, Jiasheng Shi, Mao Zhou
Abstract The wide-swath altimetry mission, Surface Water and Ocean Topography (SWOT), makes it possible to further break through the accuracy and resolution of marine gravity field recovery. However, as its main payload, the Ka-band radar interferometer (KaRIN) is easy to be affected by the spacecraft attitude, mechanical deformations and dual antenna signal reception status, which generates instrumental errors including roll errors, phase errors, baseline dilation errors, timing errors, and KaRIN noise. Together with ocean temporal variations, the instrumental errors have large effects on the SWOT Sea Surface Height (SSH) observations and hence the marine gravity field recovery. Here, taking the sea area around Japan as an example, we investigated the calibrations of instrumental errors and ocean temporal variations on the recovery of the marine gravity field. The SSH observations of SWOT are first simulated by Mean Sea Surface (MSS), Absolute Dynamic Topography (ADT), Mean Dynamic Topography (MDT) and instrumental errors. Next, the influence of instrumental errors on determining vertical deflection within single-cycle data was analyzed. Then, three calibration methods (KaRIN/KaRIN cross-calibration, Representative KaRIN/KaRIN cross-calibration, and KaRIN/Nadir cross-calibration) are used to reduce the instrumental errors; the experimental results show KaRIN/KaRIN cross-calibration is the optimal one. Last, for the multi-cycle observations containing ocean temporal variations, crossover calibration is done in single cycle and then followed by collinear adjustment in multi-cycles. This approach is verified by considering 18 simulated cycles that cover almost 1 year. Our result indicates an improvement in the accuracy of marine gravity anomaly by about 45% compared to that of one cycle. The calibration strategy of instrumental errors and ocean temporal variations can be used for high-precision marine gravity field recovery with abundant SWOT observations in the near future.
{"title":"Calibration of the Instrumental Errors on Marine Gravity Recovery from SWOT Altimeter","authors":"Gang Ma, T. Jin, Pengyuan Jiang, Jiasheng Shi, Mao Zhou","doi":"10.1080/01490419.2023.2232107","DOIUrl":"https://doi.org/10.1080/01490419.2023.2232107","url":null,"abstract":"Abstract The wide-swath altimetry mission, Surface Water and Ocean Topography (SWOT), makes it possible to further break through the accuracy and resolution of marine gravity field recovery. However, as its main payload, the Ka-band radar interferometer (KaRIN) is easy to be affected by the spacecraft attitude, mechanical deformations and dual antenna signal reception status, which generates instrumental errors including roll errors, phase errors, baseline dilation errors, timing errors, and KaRIN noise. Together with ocean temporal variations, the instrumental errors have large effects on the SWOT Sea Surface Height (SSH) observations and hence the marine gravity field recovery. Here, taking the sea area around Japan as an example, we investigated the calibrations of instrumental errors and ocean temporal variations on the recovery of the marine gravity field. The SSH observations of SWOT are first simulated by Mean Sea Surface (MSS), Absolute Dynamic Topography (ADT), Mean Dynamic Topography (MDT) and instrumental errors. Next, the influence of instrumental errors on determining vertical deflection within single-cycle data was analyzed. Then, three calibration methods (KaRIN/KaRIN cross-calibration, Representative KaRIN/KaRIN cross-calibration, and KaRIN/Nadir cross-calibration) are used to reduce the instrumental errors; the experimental results show KaRIN/KaRIN cross-calibration is the optimal one. Last, for the multi-cycle observations containing ocean temporal variations, crossover calibration is done in single cycle and then followed by collinear adjustment in multi-cycles. This approach is verified by considering 18 simulated cycles that cover almost 1 year. Our result indicates an improvement in the accuracy of marine gravity anomaly by about 45% compared to that of one cycle. The calibration strategy of instrumental errors and ocean temporal variations can be used for high-precision marine gravity field recovery with abundant SWOT observations in the near future.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"46 1","pages":"496 - 522"},"PeriodicalIF":1.6,"publicationDate":"2023-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48910963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-04DOI: 10.1080/01490419.2023.2229019
Alexa Putnam, S. Desai, R. S. Nerem
Abstract An alternative approach to empirical, non-parametric sea state bias (SSB) modeling for satellite altimeter measurements was developed with the intention of providing a simple, transparent, and efficient means to derive both a raw and smoothed SSB solution. This alternative approach, referred to as the interpolation method, maintains the flexibility to generate 2-D or 3-D models using either direct or difference measurements of the sea level anomaly uncorrected for SSB (uSLA). The final, smoothed SSB solution derived using the interpolation method is obtained over three steps, with a supplemental fourth step that consists of estimating a model-dependent dual-frequency ionosphere calibration bias to correct for a relative range + SSB error. A tandem phase analysis for all Topex/Poseidon, Jason 1-3 and Sentinel-6 Michael Freilich satellite altimeter inter-calibration periods reveals that the ionosphere calibration bias removes an ionosphere-related component from intermission bias calculations required to generate the long-term sea level record.
{"title":"Estimation of the Sea State Bias Using the Interpolation Method and Applications to Inter-Mission Calibration","authors":"Alexa Putnam, S. Desai, R. S. Nerem","doi":"10.1080/01490419.2023.2229019","DOIUrl":"https://doi.org/10.1080/01490419.2023.2229019","url":null,"abstract":"Abstract An alternative approach to empirical, non-parametric sea state bias (SSB) modeling for satellite altimeter measurements was developed with the intention of providing a simple, transparent, and efficient means to derive both a raw and smoothed SSB solution. This alternative approach, referred to as the interpolation method, maintains the flexibility to generate 2-D or 3-D models using either direct or difference measurements of the sea level anomaly uncorrected for SSB (uSLA). The final, smoothed SSB solution derived using the interpolation method is obtained over three steps, with a supplemental fourth step that consists of estimating a model-dependent dual-frequency ionosphere calibration bias to correct for a relative range + SSB error. A tandem phase analysis for all Topex/Poseidon, Jason 1-3 and Sentinel-6 Michael Freilich satellite altimeter inter-calibration periods reveals that the ionosphere calibration bias removes an ionosphere-related component from intermission bias calculations required to generate the long-term sea level record.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43076871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-19DOI: 10.1080/01490419.2023.2224513
Alexa Putnam, S. Desai, R. S. Nerem
Abstract Using an empirical, non-parametric sea state bias (SSB) modeling method, which was developed as a tool for SSB error analysis (Putnam, Alexa Forthcoming), we provide an error budget for overall SSB error, as well as the contributing sources of this error budget. The error analysis compares methods used to derive SSB models from observed altimeter measurements, collinear differences of measurements from adjacent repeat cycles, and methods using both collinear and crossover differences of measurements. Our error analysis reveals systematic error caused by ionosphere correction uncertainty in SSB models obtained from direct measurements, and wet troposphere correction uncertainty in SSB models generated using difference measurements. Results also expose a correlation to altimeter measurement error, with the backscatter coefficient accounting for over 20% of the SSB evaluation error and SWH accounting for approximately 50-60%. The error analysis presented here suggests SSB errors are lower than the often-used approximation of SSB error as 1% of SWH, except at SWH values less than 2 m where errors are likely larger. We find that increasing the pulse repetition frequency of the altimeter reduces SSB errors. The future for improving empirical, nonparametric SSB estimation primarily depends on improving measured SWH.
{"title":"Estimation of the sea state bias error budget for pulse-limited satellite altimetry","authors":"Alexa Putnam, S. Desai, R. S. Nerem","doi":"10.1080/01490419.2023.2224513","DOIUrl":"https://doi.org/10.1080/01490419.2023.2224513","url":null,"abstract":"Abstract Using an empirical, non-parametric sea state bias (SSB) modeling method, which was developed as a tool for SSB error analysis (Putnam, Alexa Forthcoming), we provide an error budget for overall SSB error, as well as the contributing sources of this error budget. The error analysis compares methods used to derive SSB models from observed altimeter measurements, collinear differences of measurements from adjacent repeat cycles, and methods using both collinear and crossover differences of measurements. Our error analysis reveals systematic error caused by ionosphere correction uncertainty in SSB models obtained from direct measurements, and wet troposphere correction uncertainty in SSB models generated using difference measurements. Results also expose a correlation to altimeter measurement error, with the backscatter coefficient accounting for over 20% of the SSB evaluation error and SWH accounting for approximately 50-60%. The error analysis presented here suggests SSB errors are lower than the often-used approximation of SSB error as 1% of SWH, except at SWH values less than 2 m where errors are likely larger. We find that increasing the pulse repetition frequency of the altimeter reduces SSB errors. The future for improving empirical, nonparametric SSB estimation primarily depends on improving measured SWH.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"46 1","pages":"460 - 478"},"PeriodicalIF":1.6,"publicationDate":"2023-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48816605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-19DOI: 10.1080/01490419.2023.2223764
Minzhi Xiang, Hongzhou Chai, Xiao Yin, Zhenqiang Du, Kaidi Jin
Abstract High-precision position, velocity and attitude information is the premise for the unmanned surface vehicle (USV) to perform various tasks. The traditional navigation technology of USV is to combine RTK (real-time kinematics) with MEMS (micro-electromechanical system). In order to avoid bi-directional communication of RTK/MEMS, a loosely coupled PPP (precise point positioning)-RTK/MEMS navigation method is proposed in this contribution, where the un-combined PPP-RTK positioning model and advanced time-differenced carrier-phase (TDCP) velocity determination model is adopted. When the reference stations are far away from the user, i.e., more than 55 km, the centimetre-level positioning results can be achieved and especially 99% horizontal error is less than 10 cm. Compared with the TDCP-only centimetre-per-second-level velocity accuracy, the proposed method can increase to accuracy of the order of millimetres per second. In terms of attitude determination accuracy, the roll and pitch are better than 0.1° and yaw is better than 0.5°, showing a similar performance to the nominal accuracy. Therefore, the proposed PPP-RTK/MEMS integration method can be a promising USV navigation solution in the offshore area.
{"title":"Precise Navigation of USV Based on PPP-RTK/MEMS in the Offshore Environment","authors":"Minzhi Xiang, Hongzhou Chai, Xiao Yin, Zhenqiang Du, Kaidi Jin","doi":"10.1080/01490419.2023.2223764","DOIUrl":"https://doi.org/10.1080/01490419.2023.2223764","url":null,"abstract":"Abstract High-precision position, velocity and attitude information is the premise for the unmanned surface vehicle (USV) to perform various tasks. The traditional navigation technology of USV is to combine RTK (real-time kinematics) with MEMS (micro-electromechanical system). In order to avoid bi-directional communication of RTK/MEMS, a loosely coupled PPP (precise point positioning)-RTK/MEMS navigation method is proposed in this contribution, where the un-combined PPP-RTK positioning model and advanced time-differenced carrier-phase (TDCP) velocity determination model is adopted. When the reference stations are far away from the user, i.e., more than 55 km, the centimetre-level positioning results can be achieved and especially 99% horizontal error is less than 10 cm. Compared with the TDCP-only centimetre-per-second-level velocity accuracy, the proposed method can increase to accuracy of the order of millimetres per second. In terms of attitude determination accuracy, the roll and pitch are better than 0.1° and yaw is better than 0.5°, showing a similar performance to the nominal accuracy. Therefore, the proposed PPP-RTK/MEMS integration method can be a promising USV navigation solution in the offshore area.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"46 1","pages":"441 - 459"},"PeriodicalIF":1.6,"publicationDate":"2023-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46772472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-29DOI: 10.1080/01490419.2023.2208289
Emily J. Tidey, R. Odolinski
Abstract The use of Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS) for accurate horizontal and vertical measurements in the marine environment has been considered since the late-1980’s and tested from the 1990’s when GPS and GLONASS were the only operational constellations available and high-cost multi-frequency receiver equipment was required. This paper modernizes the conversation using multi-constellation, low-cost, single-frequency RTK GNSS measurements and proves their value with accurate positioning and tide measurements. Our tests show average stationary horizontal positioning measurements using this equipment are suitable (95% CI) for the most stringent International Hydrographic Organization (IHO) Standard S-44 ‘Exclusive Order’ at base station ranges of up to 27 km. Vertical observations on a moving platform, smoothed using a baseline distance-dependent moving average filter show the equipment and method are comparable with traditional electronic tide gauge observations over the same base station range. All of our measurement results show the potential to improve total uncertainty calculations undertaken by hydrographers, engineers and scientists in the marine realm, while the low-cost equipment raises the possibility that more measurements can be taken, leading to improvements in monitoring, modelling and understanding the marine environment.
{"title":"Low-cost multi-GNSS, single-frequency RTK averaging for marine applications: accurate stationary positioning and vertical tide measurements","authors":"Emily J. Tidey, R. Odolinski","doi":"10.1080/01490419.2023.2208289","DOIUrl":"https://doi.org/10.1080/01490419.2023.2208289","url":null,"abstract":"Abstract The use of Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS) for accurate horizontal and vertical measurements in the marine environment has been considered since the late-1980’s and tested from the 1990’s when GPS and GLONASS were the only operational constellations available and high-cost multi-frequency receiver equipment was required. This paper modernizes the conversation using multi-constellation, low-cost, single-frequency RTK GNSS measurements and proves their value with accurate positioning and tide measurements. Our tests show average stationary horizontal positioning measurements using this equipment are suitable (95% CI) for the most stringent International Hydrographic Organization (IHO) Standard S-44 ‘Exclusive Order’ at base station ranges of up to 27 km. Vertical observations on a moving platform, smoothed using a baseline distance-dependent moving average filter show the equipment and method are comparable with traditional electronic tide gauge observations over the same base station range. All of our measurement results show the potential to improve total uncertainty calculations undertaken by hydrographers, engineers and scientists in the marine realm, while the low-cost equipment raises the possibility that more measurements can be taken, leading to improvements in monitoring, modelling and understanding the marine environment.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"46 1","pages":"333 - 358"},"PeriodicalIF":1.6,"publicationDate":"2023-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46480395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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