Abstract Over 70% of the cities in China are experiencing urbanization, and urban heat island intensity (UHII) evaluation studies have been widely performed. However, under the rapid economic development in China, few studies on surface urban heat island (SUHI) interannual variations have been conducted in coastal cities in the leading economic region of the Yangtze River Delta. In this study, the long-term summer daytime SUHI from 2001 to 2019 is studied based on the remotely sensed land surface temperature (LST) in 11 coastal cities in the Yangtze River Delta. The results show that notable SUHIs occur in the study area with high spatial heterogeneity, particularly in the central area, including Shanghai, Hangzhou, and Ningbo. The SUHI trends are not synchronous across the study area, with suburban areas revealing higher trends than city center areas. In addition, all 11 cities show an increasing trend of the urban heat proportion index (UHPI) over 19 years, which is more profound in Shanghai and Zhoushan but less profound in Lianyungang and Wenzhou. The strong correlation between the UHPI and artificial impervious coverage indicates that artificial impervious coverage plays an important role in determining the spatial and temporal distributions of the summer daytime SUHI in the 11 coastal cities, which are especially notable in Ningbo and Taizhou.
{"title":"Spatiotemporal Variations in the Urban Heat Islands across the Coastal Cities in the Yangtze River Delta, China","authors":"Xiao Shi, Yongming Xu, Guojie Wang, Yonghong Liu, Xikun Wei, Xue-Li Hu","doi":"10.1080/01490419.2021.1897716","DOIUrl":"https://doi.org/10.1080/01490419.2021.1897716","url":null,"abstract":"Abstract Over 70% of the cities in China are experiencing urbanization, and urban heat island intensity (UHII) evaluation studies have been widely performed. However, under the rapid economic development in China, few studies on surface urban heat island (SUHI) interannual variations have been conducted in coastal cities in the leading economic region of the Yangtze River Delta. In this study, the long-term summer daytime SUHI from 2001 to 2019 is studied based on the remotely sensed land surface temperature (LST) in 11 coastal cities in the Yangtze River Delta. The results show that notable SUHIs occur in the study area with high spatial heterogeneity, particularly in the central area, including Shanghai, Hangzhou, and Ningbo. The SUHI trends are not synchronous across the study area, with suburban areas revealing higher trends than city center areas. In addition, all 11 cities show an increasing trend of the urban heat proportion index (UHPI) over 19 years, which is more profound in Shanghai and Zhoushan but less profound in Lianyungang and Wenzhou. The strong correlation between the UHPI and artificial impervious coverage indicates that artificial impervious coverage plays an important role in determining the spatial and temporal distributions of the summer daytime SUHI in the 11 coastal cities, which are especially notable in Ningbo and Taizhou.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1897716","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45344095","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 : 2021-04-02DOI: 10.1080/01490419.2021.1905756
Jinhai Yu, Huan Xu, Xiaoyun Wan
Abstract In the present methods to estimate seafloor topography from gravimetric data, some parameters need be computed in advance from the known bathymetric data, which leads some uncertainties in applying the methods. To overcome such uncertainties, an analytical method to estimate the seafloor topography from the vertical gravity gradient (VGG) is introduced in the paper. Based on the expression of VGG generated by a cubic prism, the observation equations for the seabed depth are established firstly. Then, the simulation results show that the observation equations established are solvable. Especially, the piecewise bilinear interpolation is introduced to separate the influence of the far-field anomalous bodies on VGG. In addition, some imitation arithmetic examples are given in order to examine the solvability of the observation equations and estimate the accuracies of their solutions. Finally, an actual seafloor topography located in South China Sea (117.6-118.25°E, 17-17.65°N), is estimated by the method proposed in the paper, and compared with ship depth sounding, the root mean square (RMS) error of bathymetry prediction is 77 m.
{"title":"An Analytical Method to Estimate Seabed Topography Only from Vertical Gravitational Gradient","authors":"Jinhai Yu, Huan Xu, Xiaoyun Wan","doi":"10.1080/01490419.2021.1905756","DOIUrl":"https://doi.org/10.1080/01490419.2021.1905756","url":null,"abstract":"Abstract In the present methods to estimate seafloor topography from gravimetric data, some parameters need be computed in advance from the known bathymetric data, which leads some uncertainties in applying the methods. To overcome such uncertainties, an analytical method to estimate the seafloor topography from the vertical gravity gradient (VGG) is introduced in the paper. Based on the expression of VGG generated by a cubic prism, the observation equations for the seabed depth are established firstly. Then, the simulation results show that the observation equations established are solvable. Especially, the piecewise bilinear interpolation is introduced to separate the influence of the far-field anomalous bodies on VGG. In addition, some imitation arithmetic examples are given in order to examine the solvability of the observation equations and estimate the accuracies of their solutions. Finally, an actual seafloor topography located in South China Sea (117.6-118.25°E, 17-17.65°N), is estimated by the method proposed in the paper, and compared with ship depth sounding, the root mean square (RMS) error of bathymetry prediction is 77 m.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1905756","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42284736","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 : 2021-04-01DOI: 10.1080/01490419.2021.1909193
Vivek Seelanki, V. Pant
Abstract Among many other physical and biogeochemical processes, oceanic upwelling is a major contributor to the primary productivity of oceans. In the present study, sixteen models from the ‘Coupled Climate Model Inter-comparison Project phase 5’ (CMIP5) are assessed for their capability in simulating the Chlorophyll (Chl-a) concentration against satellite observations over the northern Indian Ocean. The sixteen CMIP5 models are categorized into three groups based on their relative skill, Group-A models had the highest skill and captured the phase of the bloom during summer monsoon season whereas the Group-B and Group-C models mostly failed to reproduce the Chl-a concentrations. The observed interannual variations were poorly simulated by all the CMIP5 models. Group-A models showed a negative bias in Chl-a concentration over the northern Arabian Sea and a positive bias in Chl-a simulation off Somalia over the western Indian Ocean. High Chl-a associated with the coastal upwelling along the west coasts of India and Sri Lanka was poorly simulated by CMIP5 models. The study highlights the regional deficiency in CMIP5 climate models in simulating Chl-a and the need for improved coupled physical-biogeochemical models over the tropical Indian Ocean.
{"title":"Diversity in the Simulation of Chlorophyll Concentration by CMIP5 Earth System Models over the Indian Ocean","authors":"Vivek Seelanki, V. Pant","doi":"10.1080/01490419.2021.1909193","DOIUrl":"https://doi.org/10.1080/01490419.2021.1909193","url":null,"abstract":"Abstract Among many other physical and biogeochemical processes, oceanic upwelling is a major contributor to the primary productivity of oceans. In the present study, sixteen models from the ‘Coupled Climate Model Inter-comparison Project phase 5’ (CMIP5) are assessed for their capability in simulating the Chlorophyll (Chl-a) concentration against satellite observations over the northern Indian Ocean. The sixteen CMIP5 models are categorized into three groups based on their relative skill, Group-A models had the highest skill and captured the phase of the bloom during summer monsoon season whereas the Group-B and Group-C models mostly failed to reproduce the Chl-a concentrations. The observed interannual variations were poorly simulated by all the CMIP5 models. Group-A models showed a negative bias in Chl-a concentration over the northern Arabian Sea and a positive bias in Chl-a simulation off Somalia over the western Indian Ocean. High Chl-a associated with the coastal upwelling along the west coasts of India and Sri Lanka was poorly simulated by CMIP5 models. The study highlights the regional deficiency in CMIP5 climate models in simulating Chl-a and the need for improved coupled physical-biogeochemical models over the tropical Indian Ocean.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1909193","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44244388","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 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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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.
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