Pub Date : 2021-06-15DOI: 10.1080/01490419.2021.1943577
P. Woodworth
Abstract A method is described for providing a levelling datum to a sea level record containing hourly heights (or similar) with the use of a second record from a nearby location consisting of high waters only but measured to a known datum. The method is tested using data from a pair of stations in the Thames estuary where there is a predominantly semidiurnal tide. It is then applied to the determination of a datum for an important historical sea level record at Liverpool. The historical background to that important record is explained. The limitations of the method are investigated using data from a pair of stations approximately 50 km apart on the north coast of Wales. This latter case study provides insight into which aspects of the tide contribute to inaccuracies in the method when the stations are some distance apart.
{"title":"Providing a Levelling Datum to a Tide Gauge Sea Level Record","authors":"P. Woodworth","doi":"10.1080/01490419.2021.1943577","DOIUrl":"https://doi.org/10.1080/01490419.2021.1943577","url":null,"abstract":"Abstract A method is described for providing a levelling datum to a sea level record containing hourly heights (or similar) with the use of a second record from a nearby location consisting of high waters only but measured to a known datum. The method is tested using data from a pair of stations in the Thames estuary where there is a predominantly semidiurnal tide. It is then applied to the determination of a datum for an important historical sea level record at Liverpool. The historical background to that important record is explained. The limitations of the method are investigated using data from a pair of stations approximately 50 km apart on the north coast of Wales. This latter case study provides insight into which aspects of the tide contribute to inaccuracies in the method when the stations are some distance apart.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"45 1","pages":"1 - 23"},"PeriodicalIF":1.6,"publicationDate":"2021-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1943577","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"59216470","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 A remote sensing method combining remote sensing and ground surveying is proposed to extract tidal flat topographic information via the spatial distribution characteristics of tidal flat surface features. Based on the eastern Chongming beach of the Yangtze Estuary and Landsat-5 satellite images, this study identifies the spatial distribution characteristics of tidal flat features using field-based RTK data and spectral data. The remote sensing method for extracting the geometric and physical characteristics of linear and surface geographical elements on tidal flats and the elevation assignment method are discussed. The effectiveness of this method is verified by the quality of the resultant tidal flat DEM. The results show that the use of spatial distribution features in remote sensing images can provide rich topographic information. The DEM results have an accuracy of 0.16 m, are in line with the basic topographic patterns of tidal flats, and can describe local microscale geomorphic features. This technique solves the problem of a single topographic information source in current remote sensing measurement methods and provides technical support for detecting dynamic changes in coastal zones by using remote sensing technology.
{"title":"Remote Sensing Method for Extracting Topographic Information on Tidal Flats Using Spatial Distribution Features","authors":"Y. Lijun, Xiao Yao, Jiang Jie, Yixiang Chen, Gu Yan, Sentong Zhang","doi":"10.1080/01490419.2021.1925791","DOIUrl":"https://doi.org/10.1080/01490419.2021.1925791","url":null,"abstract":"Abstract A remote sensing method combining remote sensing and ground surveying is proposed to extract tidal flat topographic information via the spatial distribution characteristics of tidal flat surface features. Based on the eastern Chongming beach of the Yangtze Estuary and Landsat-5 satellite images, this study identifies the spatial distribution characteristics of tidal flat features using field-based RTK data and spectral data. The remote sensing method for extracting the geometric and physical characteristics of linear and surface geographical elements on tidal flats and the elevation assignment method are discussed. The effectiveness of this method is verified by the quality of the resultant tidal flat DEM. The results show that the use of spatial distribution features in remote sensing images can provide rich topographic information. The DEM results have an accuracy of 0.16 m, are in line with the basic topographic patterns of tidal flats, and can describe local microscale geomorphic features. This technique solves the problem of a single topographic information source in current remote sensing measurement methods and provides technical support for detecting dynamic changes in coastal zones by using remote sensing technology.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"408 - 431"},"PeriodicalIF":1.6,"publicationDate":"2021-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1925791","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43085071","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 : 2021-06-01DOI: 10.1080/01490419.2021.1922554
K. Saha, Subhajit Sinha
Abstract Sediment characteristics and distribution analysis along the Chandipur Coast in Odisha, India was performed using a variety of techniques that include sedimentary characteristics including variation in grain size, shape and character of quartz grain surfaces (determined in light microscope and electron microscope scanning). Samples were taken from various locations representing high-tide areas and low-tide areas for analysis of the grain size, intended to determine physical properties and textural parameters such as mean, sorting, skewness and kurtosis. Grain size distribution research was conducted to characterize sedimentary transportation behaviours. CM diagram defines the rolling, saltation and graded suspension process for sediment deposition at the beach. Linear Discriminant Function (LDF) indicates the superiority of marine environment with lower deposition areas. Scanning Electron Microscope (SEM) was used to examine the quartz grains to determine the origin of the sediments and to establish the physical and chemical processes that occurred during their period of deposition in recent coastal sediments.
{"title":"Grain Size Analysis and Characterization of Sedimentary Process in Tidal Flat of Chandipur Region, East Coast of India","authors":"K. Saha, Subhajit Sinha","doi":"10.1080/01490419.2021.1922554","DOIUrl":"https://doi.org/10.1080/01490419.2021.1922554","url":null,"abstract":"Abstract Sediment characteristics and distribution analysis along the Chandipur Coast in Odisha, India was performed using a variety of techniques that include sedimentary characteristics including variation in grain size, shape and character of quartz grain surfaces (determined in light microscope and electron microscope scanning). Samples were taken from various locations representing high-tide areas and low-tide areas for analysis of the grain size, intended to determine physical properties and textural parameters such as mean, sorting, skewness and kurtosis. Grain size distribution research was conducted to characterize sedimentary transportation behaviours. CM diagram defines the rolling, saltation and graded suspension process for sediment deposition at the beach. Linear Discriminant Function (LDF) indicates the superiority of marine environment with lower deposition areas. Scanning Electron Microscope (SEM) was used to examine the quartz grains to determine the origin of the sediments and to establish the physical and chemical processes that occurred during their period of deposition in recent coastal sediments.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"485 - 503"},"PeriodicalIF":1.6,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1922554","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41908112","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 : 2021-05-24DOI: 10.1080/01490419.2021.1925788
Hequan Sun, Zeyu Li, Ruoli Shao
Abstract The seawater tracing index that characterizes the sea surface feature can be calculated using the optimal band combination of China GF-4 high-resolution multispectral data, and the distribution of sea surface currents can be retrieved from the sequential band combination data. In this paper, the methods of monitoring sea surface currents are presented in detail by processing multispectral remote sensing images generated by China GF-4 Earth Observation satellite. The sea surface currents obtained from GF-4 imagery data are compared with the sea surface currents derived from FES2014 global ocean tide model, providing a validation of the proposed methods.
{"title":"Monitoring Sea Surface Currents Based on China GF-4 Multispectral Data","authors":"Hequan Sun, Zeyu Li, Ruoli Shao","doi":"10.1080/01490419.2021.1925788","DOIUrl":"https://doi.org/10.1080/01490419.2021.1925788","url":null,"abstract":"Abstract The seawater tracing index that characterizes the sea surface feature can be calculated using the optimal band combination of China GF-4 high-resolution multispectral data, and the distribution of sea surface currents can be retrieved from the sequential band combination data. In this paper, the methods of monitoring sea surface currents are presented in detail by processing multispectral remote sensing images generated by China GF-4 Earth Observation satellite. The sea surface currents obtained from GF-4 imagery data are compared with the sea surface currents derived from FES2014 global ocean tide model, providing a validation of the proposed methods.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"531 - 553"},"PeriodicalIF":1.6,"publicationDate":"2021-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1925788","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48048293","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 : 2021-05-06DOI: 10.1080/01490419.2021.1911038
Rongxing Li
Marine Geodesy will publish a special issue on Seafloor Geodesy and Acoustic Positioning in early 2022. The guest editors will be Prof. Yuanxi Yang from Xi’an Research Institute of Surveying and Mapping (China), Prof. Tianhe Xu from Shandong University (China), and Dr. Shuqiang Xue from Chinese Academy of Surveying and Mapping (China). The submitted manuscripts should describe methods, techniques, models and algorithms for seafloor geodesy and acoustic positioning. Results related to the seafloor geodetic data processing and sonar propagation error reduction are encouraged. Topics may include, but not limited to:
{"title":"Special Issue of Marine Geodesy on Seafloor Geodesy and Acoustic Positioning","authors":"Rongxing Li","doi":"10.1080/01490419.2021.1911038","DOIUrl":"https://doi.org/10.1080/01490419.2021.1911038","url":null,"abstract":"Marine Geodesy will publish a special issue on Seafloor Geodesy and Acoustic Positioning in early 2022. The guest editors will be Prof. Yuanxi Yang from Xi’an Research Institute of Surveying and Mapping (China), Prof. Tianhe Xu from Shandong University (China), and Dr. Shuqiang Xue from Chinese Academy of Surveying and Mapping (China). The submitted manuscripts should describe methods, techniques, models and algorithms for seafloor geodesy and acoustic positioning. Results related to the seafloor geodetic data processing and sonar propagation error reduction are encouraged. Topics may include, but not limited to:","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"257 - 257"},"PeriodicalIF":1.6,"publicationDate":"2021-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1911038","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47857124","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 : 2021-05-05DOI: 10.1080/01490419.2021.1925790
K. Lowell, B. Calder
Abstract To automate extraction of bathymetric soundings from lidar point clouds, two machine learning (ML 1 ) techniques were combined with a more conventional density-based algorithm. The study area was four data “tiles” near the Florida Keys. The density-based algorithm determined the most likely depth (MLD) for a grid of “estimation nodes” (ENs). Unsupervised k-means clustering determined which EN’s MLD depth and associated soundings represented ocean depth rather than ocean surface or noise to produce a preliminary classification. An extreme gradient boosting (XGB) model was fitted to pulse return metadata – e.g. return intensity, incidence angle – to produce a final Bathy/NotBathy classification. Compared to an operationally produced reference classification, the XGB model increased global accuracy and decreased the false negative rate (FNR) – i.e. undetected bathymetry – that are most important for nautical navigation for all but one tile. Agreement between the final XGB and operational reference classifications ranged from 0.84 to 0.999. Imbalance between Bathy and NotBathy was addressed using a probability decision threshold that equalizes the FNR and the true positive rate (TPR). Two methods are presented for visually evaluating differences between the two classifications spatially and in feature-space.
{"title":"Extracting Shallow-Water Bathymetry from Lidar Point Clouds Using Pulse Attribute Data: Merging Density-Based and Machine Learning Approaches","authors":"K. Lowell, B. Calder","doi":"10.1080/01490419.2021.1925790","DOIUrl":"https://doi.org/10.1080/01490419.2021.1925790","url":null,"abstract":"Abstract To automate extraction of bathymetric soundings from lidar point clouds, two machine learning (ML 1 ) techniques were combined with a more conventional density-based algorithm. The study area was four data “tiles” near the Florida Keys. The density-based algorithm determined the most likely depth (MLD) for a grid of “estimation nodes” (ENs). Unsupervised k-means clustering determined which EN’s MLD depth and associated soundings represented ocean depth rather than ocean surface or noise to produce a preliminary classification. An extreme gradient boosting (XGB) model was fitted to pulse return metadata – e.g. return intensity, incidence angle – to produce a final Bathy/NotBathy classification. Compared to an operationally produced reference classification, the XGB model increased global accuracy and decreased the false negative rate (FNR) – i.e. undetected bathymetry – that are most important for nautical navigation for all but one tile. Agreement between the final XGB and operational reference classifications ranged from 0.84 to 0.999. Imbalance between Bathy and NotBathy was addressed using a probability decision threshold that equalizes the FNR and the true positive rate (TPR). Two methods are presented for visually evaluating differences between the two classifications spatially and in feature-space.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"259 - 286"},"PeriodicalIF":1.6,"publicationDate":"2021-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1925790","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45108089","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 : 2021-05-05DOI: 10.1080/01490419.2021.1925789
B. Misiuk, V. Lecours, M. Dolan, K. Robert
Abstract The scale dependence of benthic terrain attributes is well-accepted, and multi-scale methods are increasingly applied for benthic habitat mapping. There are, however, multiple ways to calculate terrain attributes at multiple scales, and the suitability of these approaches depends on the purpose of the analysis and data characteristics. There are currently few guidelines establishing the appropriateness of multi-scale raster calculation approaches for specific benthic habitat mapping applications. First, we identify three common purposes for calculating terrain attributes at multiple scales for benthic habitat mapping: (i) characterizing scale-specific terrain features, (ii) reducing data artefacts and errors, and (iii) reducing the mischaracterization of ground-truth data due to inaccurate sample positioning. We then define criteria that calculation approaches should fulfill to address these purposes. At two study sites, five raster terrain attributes, including measures of orientation, relative position, terrain variability, slope, and rugosity were calculated at multiple scales using four approaches to compare the suitability of the approaches for these three purposes. Results suggested that specific calculation approaches were better suited to certain tasks. A transferable parameter, termed the ‘analysis distance’, was necessary to compare attributes calculated using different approaches, and we emphasize the utility of such a parameter for facilitating the generalized comparison of terrain attributes across methods, sites, and scales.
{"title":"Evaluating the Suitability of Multi-Scale Terrain Attribute Calculation Approaches for Seabed Mapping Applications","authors":"B. Misiuk, V. Lecours, M. Dolan, K. Robert","doi":"10.1080/01490419.2021.1925789","DOIUrl":"https://doi.org/10.1080/01490419.2021.1925789","url":null,"abstract":"Abstract The scale dependence of benthic terrain attributes is well-accepted, and multi-scale methods are increasingly applied for benthic habitat mapping. There are, however, multiple ways to calculate terrain attributes at multiple scales, and the suitability of these approaches depends on the purpose of the analysis and data characteristics. There are currently few guidelines establishing the appropriateness of multi-scale raster calculation approaches for specific benthic habitat mapping applications. First, we identify three common purposes for calculating terrain attributes at multiple scales for benthic habitat mapping: (i) characterizing scale-specific terrain features, (ii) reducing data artefacts and errors, and (iii) reducing the mischaracterization of ground-truth data due to inaccurate sample positioning. We then define criteria that calculation approaches should fulfill to address these purposes. At two study sites, five raster terrain attributes, including measures of orientation, relative position, terrain variability, slope, and rugosity were calculated at multiple scales using four approaches to compare the suitability of the approaches for these three purposes. Results suggested that specific calculation approaches were better suited to certain tasks. A transferable parameter, termed the ‘analysis distance’, was necessary to compare attributes calculated using different approaches, and we emphasize the utility of such a parameter for facilitating the generalized comparison of terrain attributes across methods, sites, and scales.","PeriodicalId":49884,"journal":{"name":"Marine Geodesy","volume":"44 1","pages":"327 - 385"},"PeriodicalIF":1.6,"publicationDate":"2021-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/01490419.2021.1925789","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41501594","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 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":"44 1","pages":"467 - 484"},"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":"44 1","pages":"306 - 326"},"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":"44 1","pages":"505 - 530"},"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}
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