Abstract The shore zone is the most active zone in the atmosphere, hydrosphere, biosphere and lithosphere of nature, and has the environmental characteristics of both ocean and land. The ICESat-2 satellite provides height measurements of shore zone using a photon-counting LiDAR. The purpose of this study is to explore the application potential of ICESat-2 satellite data in shore zone classification. Saint Lawrence Island, Alaska, was chosen as the study area. Firstly, in this study, the upper and lower boundaries of the shore zone of the study area were extracted based on Google Earth images. The slope and width between the two boundaries were then calculated according to the formula. Secondly, six statistical indicators (standard deviation, relative standard deviation, average absolute deviation, relative average deviation, absolute median error and quartile deviation) related to the substrate and sediment classification that could reflect the characteristics of the shore zone profile were extracted, and the statistical indicators were used as input parameters of the softmax regression model for classification. Finally, the accuracy of the shore zone classification was validated using the ShoreZone classification system. The results show that, among the 246 shore zone sections in the study area, 86% (212) has been correctly classified. The results therefore indicate that ICESat-2 data can be used to support the characterization of shore zone morphology.
{"title":"Shore Zone Classification from ICESat-2 Data over Saint Lawrence Island","authors":"Huan Xie, Yuan Sun, Xiaoshuai Liu, Qi Xu, Yalei Guo, Shijie Liu, Xiong Xu, Sicong Liu, X. Tong","doi":"10.1080/01490419.2021.1898498","DOIUrl":"https://doi.org/10.1080/01490419.2021.1898498","url":null,"abstract":"Abstract The shore zone is the most active zone in the atmosphere, hydrosphere, biosphere and lithosphere of nature, and has the environmental characteristics of both ocean and land. The ICESat-2 satellite provides height measurements of shore zone using a photon-counting LiDAR. The purpose of this study is to explore the application potential of ICESat-2 satellite data in shore zone classification. Saint Lawrence Island, Alaska, was chosen as the study area. Firstly, in this study, the upper and lower boundaries of the shore zone of the study area were extracted based on Google Earth images. The slope and width between the two boundaries were then calculated according to the formula. Secondly, six statistical indicators (standard deviation, relative standard deviation, average absolute deviation, relative average deviation, absolute median error and quartile deviation) related to the substrate and sediment classification that could reflect the characteristics of the shore zone profile were extracted, and the statistical indicators were used as input parameters of the softmax regression model for classification. Finally, the accuracy of the shore zone classification was validated using the ShoreZone classification system. The results show that, among the 246 shore zone sections in the study area, 86% (212) has been correctly classified. The results therefore indicate that ICESat-2 data can be used to support the characterization of shore zone morphology.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"454 - 466"},"PeriodicalIF":1.6,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1898498","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44075488","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}
Abstract Currently, integrated navigation systems with the inertial navigation system (INS)/geomagnetic navigation system (GNS) have been widely used in underwater navigation of autonomous underwater vehicle (AUV). Restricting AUV to navigate in the geomagnetic suitability areas (GSA) as far as possible can effectively improve the accuracy of integrated navigation systems. In order to improve the classification accuracy of GSA, a new optimal classification method based on principal component analysis (PCA) and improved back propagation (BP) neural network is proposed. PCA is used to extract the independent characteristic parameters containing the main components. Then, considering similarity coefficient, the initial weights and thresholds of BP neural network is optimized by improved adaptive genetic algorithm (IAGA). Finally, the correspondence between the geomagnetic characteristic parameters and matching performance is established based on PCA and improved adaptive genetic algorithm and back propagation (IAGA-BP) neural network for the automatic recognition of GSA. Simulated experiments based on PCA and IAGA-BP neural network shows high classification accuracy and reliability in the GSA selection. The method could provide important support for AUV path planning, which is an effective guarantee for AUV high precision and long voyage autonomous navigation.
{"title":"Automatic Recognition of Geomagnetic Suitability Areas for Path Planning of Autonomous Underwater Vehicle","authors":"Yang Chong, Hongzhou Chai, Yonghong Li, Jian Yao, Guorui Xiao, Yunfei Guo","doi":"10.1080/01490419.2021.1906799","DOIUrl":"https://doi.org/10.1080/01490419.2021.1906799","url":null,"abstract":"Abstract Currently, integrated navigation systems with the inertial navigation system (INS)/geomagnetic navigation system (GNS) have been widely used in underwater navigation of autonomous underwater vehicle (AUV). Restricting AUV to navigate in the geomagnetic suitability areas (GSA) as far as possible can effectively improve the accuracy of integrated navigation systems. In order to improve the classification accuracy of GSA, a new optimal classification method based on principal component analysis (PCA) and improved back propagation (BP) neural network is proposed. PCA is used to extract the independent characteristic parameters containing the main components. Then, considering similarity coefficient, the initial weights and thresholds of BP neural network is optimized by improved adaptive genetic algorithm (IAGA). Finally, the correspondence between the geomagnetic characteristic parameters and matching performance is established based on PCA and improved adaptive genetic algorithm and back propagation (IAGA-BP) neural network for the automatic recognition of GSA. Simulated experiments based on PCA and IAGA-BP neural network shows high classification accuracy and reliability in the GSA selection. The method could provide important support for AUV path planning, which is an effective guarantee for AUV high precision and long voyage autonomous navigation.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"287 - 305"},"PeriodicalIF":1.6,"publicationDate":"2021-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1906799","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42488201","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 : 2021-03-24DOI: 10.1080/01490419.2021.1893873
Cherdvong Saengsupavanich
Abstract A sand spit is a deposition of sediments built up and diverging from the coast. The spit can be beneficial or create problems. Understanding and being able to forecast its evolution is the key to maximizing its advantages and minimizing its drawbacks. Along the southern Gulf of Thailand, there are 3 major sand spits, being Laem Talumpuk spit, Laem Sui spit, and Laem Tachi spit. Each individual spit’s evolution was investigated by overlaying satellite images gathered from the U.S. Geological Survey and Google Earth. Five types of equations for their evolution were tested to determine the best-fitting relationships. Although it was found that different spit characteristics followed different types of expression, polynomial equations seemed to provide satisfactory coefficients of determination for all spits in the study. Each individual spit’s length, size, and orientation could be predicted by the derived relationships. Finally, proper spit managements such as dredging, community livelihood adaptation, economic development, and even tourism promotion can be planned.
{"title":"Morphological Evolution of Sand Spits in Thailand","authors":"Cherdvong Saengsupavanich","doi":"10.1080/01490419.2021.1893873","DOIUrl":"https://doi.org/10.1080/01490419.2021.1893873","url":null,"abstract":"Abstract A sand spit is a deposition of sediments built up and diverging from the coast. The spit can be beneficial or create problems. Understanding and being able to forecast its evolution is the key to maximizing its advantages and minimizing its drawbacks. Along the southern Gulf of Thailand, there are 3 major sand spits, being Laem Talumpuk spit, Laem Sui spit, and Laem Tachi spit. Each individual spit’s evolution was investigated by overlaying satellite images gathered from the U.S. Geological Survey and Google Earth. Five types of equations for their evolution were tested to determine the best-fitting relationships. Although it was found that different spit characteristics followed different types of expression, polynomial equations seemed to provide satisfactory coefficients of determination for all spits in the study. Each individual spit’s length, size, and orientation could be predicted by the derived relationships. Finally, proper spit managements such as dredging, community livelihood adaptation, economic development, and even tourism promotion can be planned.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"432 - 453"},"PeriodicalIF":1.6,"publicationDate":"2021-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1893873","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42683689","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 : 2021-03-14DOI: 10.1080/01490419.2021.1902889
Indika Prasanna Herath Mudiyanselage, M. D. K. L. Gunathilaka, D. Welikanna
Abstract Topographic mapping and ocean charting are the outputs of two main surveying techniques for which data has been collected independently for long time. In recent years there has been a growing awareness of our coastal zones to manage our marine spaces in a more structured and sustainable manner. The requirement of this is seamless spatial data coverage across the land/sea interface. The major impediment to achieve this requirement is the absence of a consistent height datum across the land/sea interface. The main objective of this research project was to develop a vertical separation model to define the relationship between the Land surveying vertical datum (LSVD), i.e., MSL/geoid and hydrographic chart datum (CD), i.e., LAT, around Sri Lanka. The vertical datum models were analysed using IDW spatial interpolation with the assumption of the spatial autocorrelation. Polynomial curve fitting of first and the second order has been implemented and both the fitted functions show that the predictions could be made to a higher degree of certainty. The averaged separation of the CD and LSVD is about 0.3 m. The overall chart datum variation analysis suggested that the linear fit seems better with the prediction of the distribution of chart datum variation.
{"title":"Development of a Unified Vertical Reference Framework for Land and Hydrographic Surveying in Sri Lanka","authors":"Indika Prasanna Herath Mudiyanselage, M. D. K. L. Gunathilaka, D. Welikanna","doi":"10.1080/01490419.2021.1902889","DOIUrl":"https://doi.org/10.1080/01490419.2021.1902889","url":null,"abstract":"Abstract Topographic mapping and ocean charting are the outputs of two main surveying techniques for which data has been collected independently for long time. In recent years there has been a growing awareness of our coastal zones to manage our marine spaces in a more structured and sustainable manner. The requirement of this is seamless spatial data coverage across the land/sea interface. The major impediment to achieve this requirement is the absence of a consistent height datum across the land/sea interface. The main objective of this research project was to develop a vertical separation model to define the relationship between the Land surveying vertical datum (LSVD), i.e., MSL/geoid and hydrographic chart datum (CD), i.e., LAT, around Sri Lanka. The vertical datum models were analysed using IDW spatial interpolation with the assumption of the spatial autocorrelation. Polynomial curve fitting of first and the second order has been implemented and both the fitted functions show that the predictions could be made to a higher degree of certainty. The averaged separation of the CD and LSVD is about 0.3 m. The overall chart datum variation analysis suggested that the linear fit seems better with the prediction of the distribution of chart datum variation.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"238 - 256"},"PeriodicalIF":1.6,"publicationDate":"2021-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1902889","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42682607","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 : 2021-03-11DOI: 10.1080/01490419.2021.1889727
T. Saari, M. Bilker‐Koivula, H. Koivula, M. Nordman, P. Häkli, S. Lahtinen
Abstract Traditionally, geoid models have been validated using GNSS-levelling benchmarks on land only. As such benchmarks cannot be established offshore, marine areas of geoid models must be evaluated in a different way. In this research, we present a marine GNSS/gravity campaign where existing geoid models were validated at sea areas by GNSS measurements in combination with sea surface models. Additionally, a new geoid model, calculated using the newly collected marine gravity data, was validated. The campaign was carried out with the marine geology research catamaran Geomari (operated by the Geological Survey of Finland), which sailed back and forth the eastern part of the Finnish territorial waters of the Gulf of Finland during the early summer of 2018. From the GNSS and sea surface data we were able to obtain geoid heights at sea areas with an accuracy of a few centimetres. When the GNSS derived geoid heights are compared with geoid heights from the geoid models differences between the respective models are seen in the most eastern and southern parts of the campaign area. The new gravity data changed the geoid model heights by up to 15 cm in areas of sparse/non-existing gravity data.
{"title":"Validating Geoid Models with Marine GNSS Measurements, Sea Surface Models, and Additional Gravity Observations in the Gulf of Finland","authors":"T. Saari, M. Bilker‐Koivula, H. Koivula, M. Nordman, P. Häkli, S. Lahtinen","doi":"10.1080/01490419.2021.1889727","DOIUrl":"https://doi.org/10.1080/01490419.2021.1889727","url":null,"abstract":"Abstract Traditionally, geoid models have been validated using GNSS-levelling benchmarks on land only. As such benchmarks cannot be established offshore, marine areas of geoid models must be evaluated in a different way. In this research, we present a marine GNSS/gravity campaign where existing geoid models were validated at sea areas by GNSS measurements in combination with sea surface models. Additionally, a new geoid model, calculated using the newly collected marine gravity data, was validated. The campaign was carried out with the marine geology research catamaran Geomari (operated by the Geological Survey of Finland), which sailed back and forth the eastern part of the Finnish territorial waters of the Gulf of Finland during the early summer of 2018. From the GNSS and sea surface data we were able to obtain geoid heights at sea areas with an accuracy of a few centimetres. When the GNSS derived geoid heights are compared with geoid heights from the geoid models differences between the respective models are seen in the most eastern and southern parts of the campaign area. The new gravity data changed the geoid model heights by up to 15 cm in areas of sparse/non-existing gravity data.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"196 - 214"},"PeriodicalIF":1.6,"publicationDate":"2021-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1889727","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49097710","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 : 2021-03-11DOI: 10.1080/01490419.2021.1887014
Jiawei Du, Fang Wu, Ruixing Xing, Jinghan Li, Xianyong Gong
Abstract Maritime structures are significant man-made objects located along coastlines that have drawn considerable attention in maritime navigation, coastal engineering, and urban planning. During the process of map generalization, some maritime structures need to be collapsed. In our study, first, the representation characteristics of these maritime structures are analysed. Second, based on these characteristics, an automated approach of identifying these maritime structures that will potentially be collapsed while simultaneously extracting their partially proportional symbols is developed. Third, based on scale-driven thresholds, the collapse method is automated by selecting extracted partially proportional symbols and is collaborated with coastline simplification. Finally, the proposed approach is tested on various coastlines and maritime structures, and the experimental results demonstrate that our approach is effective for collapsing maritime structures and collaborating with the simplification operator for the automated generalization of coastlines.
{"title":"An Automated Approach to Coastline Simplification for Maritime Structures with Collapse Operation","authors":"Jiawei Du, Fang Wu, Ruixing Xing, Jinghan Li, Xianyong Gong","doi":"10.1080/01490419.2021.1887014","DOIUrl":"https://doi.org/10.1080/01490419.2021.1887014","url":null,"abstract":"Abstract Maritime structures are significant man-made objects located along coastlines that have drawn considerable attention in maritime navigation, coastal engineering, and urban planning. During the process of map generalization, some maritime structures need to be collapsed. In our study, first, the representation characteristics of these maritime structures are analysed. Second, based on these characteristics, an automated approach of identifying these maritime structures that will potentially be collapsed while simultaneously extracting their partially proportional symbols is developed. Third, based on scale-driven thresholds, the collapse method is automated by selecting extracted partially proportional symbols and is collaborated with coastline simplification. Finally, the proposed approach is tested on various coastlines and maritime structures, and the experimental results demonstrate that our approach is effective for collapsing maritime structures and collaborating with the simplification operator for the automated generalization of coastlines.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"157 - 195"},"PeriodicalIF":1.6,"publicationDate":"2021-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1887014","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48011792","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 : 2021-03-06DOI: 10.1080/01490419.2021.1894273
L. Pandey, S. Dwivedi, Matthew J. Martin
Abstract An ocean circulation model, Nucleus for European Modelling of the Ocean (NEMO version 3.6) is customized to run at high-resolution over a regional domain [30oE-105oE; 20oS-30oN] in the Indian Ocean. It uses horizontal resolution of 1/12° in longitude/latitude and 75 levels in the vertical direction. The model well captures the observed space-time variations of temperature and salinity at the surface and subsurface, and the surface currents and eddy kinetic energy. The short-term spatio-temporal predictability of the Bay of Bengal (BoB) region is quantified using the model currents. The Lagrangian measure of predictability, Finite Time Lyapunov Exponent (FTLE) is compared with the Eulerian measure (Okubo-Weiss parameter). The regions of chaotic stirring are identified in the BoB. The FTLE analysis reveals that the predictability on a biweekly time scale in the BoB is minimum during October-November, and the highest during May to July. The FTLE is shown to serve as a useful tool for planning targeted observations in the BoB region.
{"title":"Short-Term Predictability of the Bay of Bengal Region Using a High-Resolution Indian Ocean Model","authors":"L. Pandey, S. Dwivedi, Matthew J. Martin","doi":"10.1080/01490419.2021.1894273","DOIUrl":"https://doi.org/10.1080/01490419.2021.1894273","url":null,"abstract":"Abstract An ocean circulation model, Nucleus for European Modelling of the Ocean (NEMO version 3.6) is customized to run at high-resolution over a regional domain [30oE-105oE; 20oS-30oN] in the Indian Ocean. It uses horizontal resolution of 1/12° in longitude/latitude and 75 levels in the vertical direction. The model well captures the observed space-time variations of temperature and salinity at the surface and subsurface, and the surface currents and eddy kinetic energy. The short-term spatio-temporal predictability of the Bay of Bengal (BoB) region is quantified using the model currents. The Lagrangian measure of predictability, Finite Time Lyapunov Exponent (FTLE) is compared with the Eulerian measure (Okubo-Weiss parameter). The regions of chaotic stirring are identified in the BoB. The FTLE analysis reveals that the predictability on a biweekly time scale in the BoB is minimum during October-November, and the highest during May to July. The FTLE is shown to serve as a useful tool for planning targeted observations in the BoB region.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"215 - 237"},"PeriodicalIF":1.6,"publicationDate":"2021-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1894273","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47489109","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 : 2021-01-27DOI: 10.1080/01490419.2021.1879330
Casey O’Heran, B. Calder
Abstract Knowledge of offset vectors from vessel mounted sonars, to systems such as Inertial Measurement Units and Global Navigation Satellite Systems is crucial for accurate ocean mapping applications. Traditional survey methods, such as employing laser scanners or total stations, are used to determine professional vessel offset distances reliably. However, for vessels of opportunity that are collecting volunteer bathymetric data, it is beneficial to consider survey methods that may be less time consuming, less expensive, or which do not involve bringing the vessel into a dry dock. Thus, this article explores two alternative methods that meet this criterion for horizontally calibrating vessels. Unmanned Aircraft Systems (UASs) were used to horizontally calibrate a vessel with both Structure from Motion photogrammetry and aerial lidar while the vessel was moored to a floating dock. Estimates of the horizontal deviations from ground truth, were obtained by comparing the horizontal distances between targets on a vessel, acquired by the UAS methods, to multiple ground truth sources: a survey-grade terrestrial laser scan and fiberglass tape measurements. The investigated methods were able to achieve horizontal deviations on the order of centimeters with the use of Ground Control Points.
{"title":"Horizontal Calibration of Vessels with UASs","authors":"Casey O’Heran, B. Calder","doi":"10.1080/01490419.2021.1879330","DOIUrl":"https://doi.org/10.1080/01490419.2021.1879330","url":null,"abstract":"Abstract Knowledge of offset vectors from vessel mounted sonars, to systems such as Inertial Measurement Units and Global Navigation Satellite Systems is crucial for accurate ocean mapping applications. Traditional survey methods, such as employing laser scanners or total stations, are used to determine professional vessel offset distances reliably. However, for vessels of opportunity that are collecting volunteer bathymetric data, it is beneficial to consider survey methods that may be less time consuming, less expensive, or which do not involve bringing the vessel into a dry dock. Thus, this article explores two alternative methods that meet this criterion for horizontally calibrating vessels. Unmanned Aircraft Systems (UASs) were used to horizontally calibrate a vessel with both Structure from Motion photogrammetry and aerial lidar while the vessel was moored to a floating dock. Estimates of the horizontal deviations from ground truth, were obtained by comparing the horizontal distances between targets on a vessel, acquired by the UAS methods, to multiple ground truth sources: a survey-grade terrestrial laser scan and fiberglass tape measurements. The investigated methods were able to achieve horizontal deviations on the order of centimeters with the use of Ground Control Points.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"91 - 107"},"PeriodicalIF":1.6,"publicationDate":"2021-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1879330","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41414762","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 : 2021-01-02DOI: 10.1080/01490419.2020.1835758
L. Pandey, S. Dwivedi
Abstract The performance of vertical parameterization schemes, namely, turbulent kinetic energy (TKE) and K-profile parameterization (KPP), is evaluated over the domain [30E-120E; 20S-30N] in the Indian Ocean using the Nucleus for European Modeling of the Ocean (NEMO) regional model. The surface and sub-surface hydrography and mixed layer depth (MLD) of the simulations using TKE and KPP schemes have been compared. The KPP scheme produces higher bias (∼0.5 °C) of sea surface temperature (SST) in monsoon and post-monsoon seasons, which reduces on using the TKE scheme. The maximum surface salinity difference (0.45 psu) between TKE and KPP simulations is obtained over the head Bay of Bengal (BoB) in the post-monsoon months. The KPP scheme also overestimates MLD of the region. Barring highly convective regions as well as regions marked with very low and rapidly changing salinity, the TKE scheme performs better than KPP scheme in simulating the hydrography and MLD of the region. The differences between TKE and KPP simulations in the vertical stability and mixing are studied using buoyancy frequency, vertical shear of horizontal currents and energy required for mixing as quantifiers. The mixed layer heat budget analysis explains seasonal variability of SST and differences in vertical mixing parameterizations.
{"title":"Comparing the Performance of Turbulent Kinetic Energy and K-Profile Parameterization Vertical Parameterization Schemes over the Tropical Indian Ocean","authors":"L. Pandey, S. Dwivedi","doi":"10.1080/01490419.2020.1835758","DOIUrl":"https://doi.org/10.1080/01490419.2020.1835758","url":null,"abstract":"Abstract The performance of vertical parameterization schemes, namely, turbulent kinetic energy (TKE) and K-profile parameterization (KPP), is evaluated over the domain [30E-120E; 20S-30N] in the Indian Ocean using the Nucleus for European Modeling of the Ocean (NEMO) regional model. The surface and sub-surface hydrography and mixed layer depth (MLD) of the simulations using TKE and KPP schemes have been compared. The KPP scheme produces higher bias (∼0.5 °C) of sea surface temperature (SST) in monsoon and post-monsoon seasons, which reduces on using the TKE scheme. The maximum surface salinity difference (0.45 psu) between TKE and KPP simulations is obtained over the head Bay of Bengal (BoB) in the post-monsoon months. The KPP scheme also overestimates MLD of the region. Barring highly convective regions as well as regions marked with very low and rapidly changing salinity, the TKE scheme performs better than KPP scheme in simulating the hydrography and MLD of the region. The differences between TKE and KPP simulations in the vertical stability and mixing are studied using buoyancy frequency, vertical shear of horizontal currents and energy required for mixing as quantifiers. The mixed layer heat budget analysis explains seasonal variability of SST and differences in vertical mixing parameterizations.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"42 - 69"},"PeriodicalIF":1.6,"publicationDate":"2021-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2020.1835758","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43245100","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 : 2020-12-10DOI: 10.1080/01490419.2020.1861138
Zhiqiang Zhang, Jiancheng Li, Kai-Jun Zhang, R. Yu
Abstract Autonomous underwater vehicle (AUV) can be controlled autonomously and cable-less, which can reduce the cost and has good applicability for underwater gravity measurement. Based on airborne gravity measurement, the basic principle of underwater moving gravity measurement is studied, and the mathematical model of AUV underwater moving gravity measurement is established, which based on the data obtained by the gravimeter with a fibre optic inertial navigation system (INS), short baseline underwater acoustic positioning (SBL), Doppler velocity log (DVL) and depth gauge (DG). Underwater experimental verification system of moving gravity measurement consists of the reformed BQR800 Unmanned Underwater Vehicle and dg-M strapdown gravimeter. Mulan Lake in Wuhan was selected as the experimental site. Experimental scheme and processing flow of underwater moving gravity measurement data was designed. Data obtained by strapdown gravimeter, DG, DVL, SBL and other equipment was analysed, and the data calculation was completed. Moreover, the repetition lines are selected to evaluate the repeatability of gravity measurement. The experiment al verification of gravity measurement for three return trips were carried out from January 7 to 8, 2020. The accuracy of repetition line reached 0.42 mGal, which verified the feasibility of underwater moving gravity measurement.
{"title":"Experimental Study on Underwater Moving Gravity Measurement by Using Strapdown Gravimeter Based on AUV Platform","authors":"Zhiqiang Zhang, Jiancheng Li, Kai-Jun Zhang, R. Yu","doi":"10.1080/01490419.2020.1861138","DOIUrl":"https://doi.org/10.1080/01490419.2020.1861138","url":null,"abstract":"Abstract Autonomous underwater vehicle (AUV) can be controlled autonomously and cable-less, which can reduce the cost and has good applicability for underwater gravity measurement. Based on airborne gravity measurement, the basic principle of underwater moving gravity measurement is studied, and the mathematical model of AUV underwater moving gravity measurement is established, which based on the data obtained by the gravimeter with a fibre optic inertial navigation system (INS), short baseline underwater acoustic positioning (SBL), Doppler velocity log (DVL) and depth gauge (DG). Underwater experimental verification system of moving gravity measurement consists of the reformed BQR800 Unmanned Underwater Vehicle and dg-M strapdown gravimeter. Mulan Lake in Wuhan was selected as the experimental site. Experimental scheme and processing flow of underwater moving gravity measurement data was designed. Data obtained by strapdown gravimeter, DG, DVL, SBL and other equipment was analysed, and the data calculation was completed. Moreover, the repetition lines are selected to evaluate the repeatability of gravity measurement. The experiment al verification of gravity measurement for three return trips were carried out from January 7 to 8, 2020. The accuracy of repetition line reached 0.42 mGal, which verified the feasibility of underwater moving gravity measurement.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"108 - 135"},"PeriodicalIF":1.6,"publicationDate":"2020-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2020.1861138","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48997773","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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