Pub Date : 2014-09-01DOI: 10.1260/1759-3131.5.3.163
R. Vijaya, A. Kiran, R. Ramesh, M. Ramanamurthy, G. Ramadass, M. Atmanand
Suction pile anchors are large cylindrical (inverted bucket type structure) open at the bottom and closed at the top and largely used for mooring of offshore platforms, exploratory vessels etc. Prediction of the mooring capacity of suction piles is a critical issue faced by the design engineers and rational methods are required to produce reliable designs. Tests have been conducted in an existing natural pond within NIOT campus with the objective of developing methodology of deployment, design and logistics for suction pile installation and testing of mooring capacity under static pullout. Small size suction piles with varying diameters and lengths have been used in the tests. The tests have been carried out in the natural pond with constant water depth of 1.5 m with the top 1.5 m layer of bed comprising soft marine clay. It is found that pile geometry, aspect ratio and angle of pullout have a significant influence on the response to pullout. As angle of mooring load application changes from vertical to horizontal the reaction offered by the suction pile changes from skin friction to passive soil resistance. Resistance offered by the internal plug of soil is found to vary according to dimension of the anchor piles.
{"title":"Assessment of Feasibility of Suction Pile/Anchor Installation and Pullout Testing through Field Tests","authors":"R. Vijaya, A. Kiran, R. Ramesh, M. Ramanamurthy, G. Ramadass, M. Atmanand","doi":"10.1260/1759-3131.5.3.163","DOIUrl":"https://doi.org/10.1260/1759-3131.5.3.163","url":null,"abstract":"Suction pile anchors are large cylindrical (inverted bucket type structure) open at the bottom and closed at the top and largely used for mooring of offshore platforms, exploratory vessels etc. Prediction of the mooring capacity of suction piles is a critical issue faced by the design engineers and rational methods are required to produce reliable designs. Tests have been conducted in an existing natural pond within NIOT campus with the objective of developing methodology of deployment, design and logistics for suction pile installation and testing of mooring capacity under static pullout. Small size suction piles with varying diameters and lengths have been used in the tests. The tests have been carried out in the natural pond with constant water depth of 1.5 m with the top 1.5 m layer of bed comprising soft marine clay. It is found that pile geometry, aspect ratio and angle of pullout have a significant influence on the response to pullout. As angle of mooring load application changes from vertical to horizontal the reaction offered by the suction pile changes from skin friction to passive soil resistance. Resistance offered by the internal plug of soil is found to vary according to dimension of the anchor piles.","PeriodicalId":105024,"journal":{"name":"The International Journal of Ocean and Climate Systems","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114829821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.1260/1759-3131.5.3.151
A. Hegde, S. Naseeb
The paper presents the results of a series of laboratory experiments that were conducted in a 2D monochromatic wave flume of the department to evaluate the transmission characteristics of scaled down semicircular breakwater (SBW) physical models of different radii (R) for different submergence ratios (d/hc), where d is the depth of water and hc is the height of the breakwater crest from the sea bed. The radii of the breakwater models studied were 20 cm, 22.5 cm, 25 cm, and 27.5 cm and d/hc values used varied from 1.067 to 1.667. The wave climate along the Mangalore coast of India was used for arriving at the various wave parameters. Incident wave heights (Hi) used varied from 3 to 18 cm, wave periods (T) ranged from 1.2 s to 2.2 s with water depths (d) of 40 cm, 45 cm and 50 cm. The data collected was analyzed by plotting the non-dimensional graphs depicting the variation of transmission coefficient Kt (Kt = Ht/Hi, where Ht = transmitted wave height) with wave steepness Hi/gT2 for different R/Hi and d/hc values. It was found that transmission coefficient decreased as the incident wave steepness increased for different submergence ratios. Also as d/hc increased, it was found that Kt increased initially and then decreased.
{"title":"Transmission Performance of Submerged Semicircular Breakwaters for Different Radii and Submergence Ratios","authors":"A. Hegde, S. Naseeb","doi":"10.1260/1759-3131.5.3.151","DOIUrl":"https://doi.org/10.1260/1759-3131.5.3.151","url":null,"abstract":"The paper presents the results of a series of laboratory experiments that were conducted in a 2D monochromatic wave flume of the department to evaluate the transmission characteristics of scaled down semicircular breakwater (SBW) physical models of different radii (R) for different submergence ratios (d/hc), where d is the depth of water and hc is the height of the breakwater crest from the sea bed. The radii of the breakwater models studied were 20 cm, 22.5 cm, 25 cm, and 27.5 cm and d/hc values used varied from 1.067 to 1.667. The wave climate along the Mangalore coast of India was used for arriving at the various wave parameters. Incident wave heights (Hi) used varied from 3 to 18 cm, wave periods (T) ranged from 1.2 s to 2.2 s with water depths (d) of 40 cm, 45 cm and 50 cm. The data collected was analyzed by plotting the non-dimensional graphs depicting the variation of transmission coefficient Kt (Kt = Ht/Hi, where Ht = transmitted wave height) with wave steepness Hi/gT2 for different R/Hi and d/hc values. It was found that transmission coefficient decreased as the incident wave steepness increased for different submergence ratios. Also as d/hc increased, it was found that Kt increased initially and then decreased.","PeriodicalId":105024,"journal":{"name":"The International Journal of Ocean and Climate Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114403607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-01DOI: 10.1260/1759-3131.5.2.79
N. Harish, N. Lokesha, S. Mandal, Subba Rao, S. Patil
In the present study, Support Vector Machines (SVM) and hybrid of Genetic Algorithm (GA) with SVM models are developed to predict the damage level of non-reshaped berm breakwaters. Optimal kernel parameters of SVM are determined by using GA algorithm. The models are trained and tested on the data set obtained from the experiments which were carried out at Marine Structures Laboratory, Department of Applied Mechanics and Hydraulics, National Institute of Technology Karnataka, Surathkal, India. The results of SVM and GA-SVM models are compared in terms of statistical measures like correlation coefficient, root mean square error and scatter index. The results on SVM and GA-SVM models reveals that the performance of GA-SVM is better compared to SVM models in predicting the damage level of non-reshaped berm breakwater.
{"title":"Parameter Optimization Using GA in SVM to Predict Damage Level of Non-Reshaped Berm Breakwater","authors":"N. Harish, N. Lokesha, S. Mandal, Subba Rao, S. Patil","doi":"10.1260/1759-3131.5.2.79","DOIUrl":"https://doi.org/10.1260/1759-3131.5.2.79","url":null,"abstract":"In the present study, Support Vector Machines (SVM) and hybrid of Genetic Algorithm (GA) with SVM models are developed to predict the damage level of non-reshaped berm breakwaters. Optimal kernel parameters of SVM are determined by using GA algorithm. The models are trained and tested on the data set obtained from the experiments which were carried out at Marine Structures Laboratory, Department of Applied Mechanics and Hydraulics, National Institute of Technology Karnataka, Surathkal, India. The results of SVM and GA-SVM models are compared in terms of statistical measures like correlation coefficient, root mean square error and scatter index. The results on SVM and GA-SVM models reveals that the performance of GA-SVM is better compared to SVM models in predicting the damage level of non-reshaped berm breakwater.","PeriodicalId":105024,"journal":{"name":"The International Journal of Ocean and Climate Systems","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126267312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-01DOI: 10.1260/1759-3131.5.2.39
A. Babanin, W. Rogers
Rogue waves are abnormally high, with respect to the mean, waves in the ocean. Present understanding of their nature will be reviewed and discussed. Rogue waves can be due to quasi-linear superpositions of waves and nonlinear effects such as instabilities of wave trains. Both appear to be important and possible. Individual waves can be focused into a superposition due to either dispersive or directional features of wave fields. While probability of the former in oceanic conditions is very low, the directional focusing appears to be rare but regular events. Nonlinear wave fields should be separated into stable and unstable conditions, with different probability distributions for wave heights/crests. In stable conditions, wave statistics are determined by the quasi-linear focusing, whereas in unstable wave trains high transient wave events can occur. Their maximal height/steepness is determined by combined dynamics of the instability growth and the limiting wave breaking.
{"title":"Generation and Limiters of Rogue Waves","authors":"A. Babanin, W. Rogers","doi":"10.1260/1759-3131.5.2.39","DOIUrl":"https://doi.org/10.1260/1759-3131.5.2.39","url":null,"abstract":"Rogue waves are abnormally high, with respect to the mean, waves in the ocean. Present understanding of their nature will be reviewed and discussed. Rogue waves can be due to quasi-linear superpositions of waves and nonlinear effects such as instabilities of wave trains. Both appear to be important and possible. Individual waves can be focused into a superposition due to either dispersive or directional features of wave fields. While probability of the former in oceanic conditions is very low, the directional focusing appears to be rare but regular events. Nonlinear wave fields should be separated into stable and unstable conditions, with different probability distributions for wave heights/crests. In stable conditions, wave statistics are determined by the quasi-linear focusing, whereas in unstable wave trains high transient wave events can occur. Their maximal height/steepness is determined by combined dynamics of the instability growth and the limiting wave breaking.","PeriodicalId":105024,"journal":{"name":"The International Journal of Ocean and Climate Systems","volume":"115 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134565323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-01DOI: 10.1260/1759-3131.5.2.51
Rameez Badhurshah, A. Samad, J. Sangwai
Oscillating water column based wave energy device uses bi-directional flow impulse turbine. In this paper, a computational analysis of an impulse turbine has been performed using Ansys-CFX 14.0 code. Initially, a CAD model was prepared and unstructured meshing strategy was implemented in the flow domain. Reynolds-averaged Navier Stokes equations were solved to analyse the fluid flow properties. The efficiency, torque coefficient and input coefficient were compared for the evaluations. The flow features through the turbine shows that the flow separation occurs near the trailing edge of the suction surface of the blade.
{"title":"Analysis of Flow through Ocean Energy Harvesting Bidirectional Impulse Turbine","authors":"Rameez Badhurshah, A. Samad, J. Sangwai","doi":"10.1260/1759-3131.5.2.51","DOIUrl":"https://doi.org/10.1260/1759-3131.5.2.51","url":null,"abstract":"Oscillating water column based wave energy device uses bi-directional flow impulse turbine. In this paper, a computational analysis of an impulse turbine has been performed using Ansys-CFX 14.0 code. Initially, a CAD model was prepared and unstructured meshing strategy was implemented in the flow domain. Reynolds-averaged Navier Stokes equations were solved to analyse the fluid flow properties. The efficiency, torque coefficient and input coefficient were compared for the evaluations. The flow features through the turbine shows that the flow separation occurs near the trailing edge of the suction surface of the blade.","PeriodicalId":105024,"journal":{"name":"The International Journal of Ocean and Climate Systems","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125111502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-01DOI: 10.1260/1759-3131.5.2.105
R. Sundaravadivelu, Rahul Kanotra, N. Srinivasan
With the advancement of oil & gas into ultra deepwater, the need for drilling and production platforms has becomes more acute. The dry tree semisubmersible can be used for direct vertical access into reservoirs from deepwater since it offers small in-place motions, large open deck areas, dockside commissioning and minimum offshore hookup. The direct access allows the operator to drill, complete and work over the well directly from the same platform. The drytree semisubmersible consists of a keel tank which can be telescoped up and down based on the requirement of the platform. The keel tank is fully telescoped down while in operating condition and telescoped up while in transportation condition. The transportation analysis of a drytree semisubmersible using the linear radiation, diffraction panel program WAMIT is presented in this paper. Parametric studies were carried out in WAMIT by varying the size of the keel tank by considering the keel tank size as 80X80m, 91.5X91.5m and 100X100m. The Case 2 in which the keel tank dimensions were 91.5×91.5 m was found to be most appropriate of all, as the response for it was lower compared to other cases and also the structure was good from stability point of view. It was found that the heave and response were high only beyond 15 seconds wave period thus making transportation operations safe, as transportation is carried out in sea states 5 and 6 which have wave periods less than 14 seconds. Also the pitch RAO was found to be very low thus posing no threat in transportation mode.
{"title":"Transportation Analysis of Dry Tree Semisubmersible","authors":"R. Sundaravadivelu, Rahul Kanotra, N. Srinivasan","doi":"10.1260/1759-3131.5.2.105","DOIUrl":"https://doi.org/10.1260/1759-3131.5.2.105","url":null,"abstract":"With the advancement of oil & gas into ultra deepwater, the need for drilling and production platforms has becomes more acute. The dry tree semisubmersible can be used for direct vertical access into reservoirs from deepwater since it offers small in-place motions, large open deck areas, dockside commissioning and minimum offshore hookup. The direct access allows the operator to drill, complete and work over the well directly from the same platform. The drytree semisubmersible consists of a keel tank which can be telescoped up and down based on the requirement of the platform. The keel tank is fully telescoped down while in operating condition and telescoped up while in transportation condition. The transportation analysis of a drytree semisubmersible using the linear radiation, diffraction panel program WAMIT is presented in this paper. Parametric studies were carried out in WAMIT by varying the size of the keel tank by considering the keel tank size as 80X80m, 91.5X91.5m and 100X100m. The Case 2 in which the keel tank dimensions were 91.5×91.5 m was found to be most appropriate of all, as the response for it was lower compared to other cases and also the structure was good from stability point of view. It was found that the heave and response were high only beyond 15 seconds wave period thus making transportation operations safe, as transportation is carried out in sea states 5 and 6 which have wave periods less than 14 seconds. Also the pitch RAO was found to be very low thus posing no threat in transportation mode.","PeriodicalId":105024,"journal":{"name":"The International Journal of Ocean and Climate Systems","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127021104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-01DOI: 10.1260/1759-3131.5.2.89
G. Saravanan, S. Sannasiraj, V. Sundar
An Asymptotic solution of liquid sloshing motion in a rectangular tank is presented based on the potential flow theory. A rectangular tank is excited harmonically, in the sway and heave modes. The Stokes perturbation theory is used to resolve the boundary value problem. The perturbed problem reduces to the non-homogeneous Mathieu's equation in the case of coupled harmonic excitations, which induces the sloshing motion subjected to parametric rolling of the tank. Lindstedt-Poincare’ method is used to determine the stable solution of the Mathieu's equation.
{"title":"Asymptotic Analysis of Sloshing in a Rectangular Tank","authors":"G. Saravanan, S. Sannasiraj, V. Sundar","doi":"10.1260/1759-3131.5.2.89","DOIUrl":"https://doi.org/10.1260/1759-3131.5.2.89","url":null,"abstract":"An Asymptotic solution of liquid sloshing motion in a rectangular tank is presented based on the potential flow theory. A rectangular tank is excited harmonically, in the sway and heave modes. The Stokes perturbation theory is used to resolve the boundary value problem. The perturbed problem reduces to the non-homogeneous Mathieu's equation in the case of coupled harmonic excitations, which induces the sloshing motion subjected to parametric rolling of the tank. Lindstedt-Poincare’ method is used to determine the stable solution of the Mathieu's equation.","PeriodicalId":105024,"journal":{"name":"The International Journal of Ocean and Climate Systems","volume":"280 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132519050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-01DOI: 10.1260/1759-3131.5.2.65
S. Patil, S. Mandal, A. Hegde
Understanding the physics of complex system plays an important role in selection of data for training intelligent computing models. Based on the physics of the wave transmission of Horizontally Interlaced Multilayer Moored Floating Pipe Breakwater, a laboratory experiment carried out at Department of Applied Mechanics, National Institute of Technology Surathkal, India, authors felt that relative depth of water (d/L) may have effect on the performance of intelligent computing models. In the present paper, d/L is taken as one of the inputs to study the performance of ANN and Genetic Algorithm based Support Vector Machine Regression (GA-SVMR) model which was ignored by the authors in their previous studies. The performances of present ANN-1 and GA-SVMR-1 models are compared with the previous ANN and GA-SVMR models. The results revealed that there is a slight improvement in the performance of present ANN-1 and GA-SVMR-1 models in terms of Correlation Coefficient.
{"title":"Effect of Water Depth on the Performance of Intelligent Computing Models in Predicting Wave Transmission of Floating Pipe Breakwater","authors":"S. Patil, S. Mandal, A. Hegde","doi":"10.1260/1759-3131.5.2.65","DOIUrl":"https://doi.org/10.1260/1759-3131.5.2.65","url":null,"abstract":"Understanding the physics of complex system plays an important role in selection of data for training intelligent computing models. Based on the physics of the wave transmission of Horizontally Interlaced Multilayer Moored Floating Pipe Breakwater, a laboratory experiment carried out at Department of Applied Mechanics, National Institute of Technology Surathkal, India, authors felt that relative depth of water (d/L) may have effect on the performance of intelligent computing models. In the present paper, d/L is taken as one of the inputs to study the performance of ANN and Genetic Algorithm based Support Vector Machine Regression (GA-SVMR) model which was ignored by the authors in their previous studies. The performances of present ANN-1 and GA-SVMR-1 models are compared with the previous ANN and GA-SVMR models. The results revealed that there is a slight improvement in the performance of present ANN-1 and GA-SVMR-1 models in terms of Correlation Coefficient.","PeriodicalId":105024,"journal":{"name":"The International Journal of Ocean and Climate Systems","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125698782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-03-01DOI: 10.1260/1759-3131.5.1.23
K. Parvathy, D. Gopinath, V. Noujas, K. V. Thomas
Nearshore wave transformation is a complex coastal process of shoaling, refraction, diffraction, reflection, and energy dissipation due to bed friction and breaking contributing variations in the wave height, period and direction. A well defined sediment cell of about 45 km extending from Kovalam headland to Varkala cliff which forms a part of Thiruvananthapuram coast along the southwest coast of India, is selected for the wave transformation studies. In the present study MIKE 21 Spectral Wave model (DHI, 2011) was used. The model simulates the growth, decay and transformation of wind generated waves and swells both in offshore and coastal areas. Providing MIKE 21 SW with a suitable bathymetry is essential for obtaining reliable results from the model. Usually the offshore bathymetry is derived from C-MAP, ETOPO, GEBCO etc. and the nearshore bathymetry is generated from close grid bathymetric surveys. In this study offshore bathymetry was generated from GEBCO-08 grid which is a freely available software with 30 arc (∼ 1 km) resolution. In the nearshore zone, surveyed close grid bathymetric data were used. The other inputs such as wave measurements and wind data provided in the model were from observations in Lakshadweep Sea. Model result is calibrated with field observations along this sector. The model has efficiently simulated the process of shoaling and refraction along the coast. The percentage of observed shoaling is 12.7% at a distance of 24 km from the shoreline at a depth of 70m and it was seen to be increasing to 27.9% when it reached around 2.4 km from the shore at a depth of 10m. The model result also shows that the wave is almost aligned parallel to the coast as wave approaches the coast. This model result can be used for further applications in designing along this coast.
{"title":"Wave Transformation along Southwest Coast of India Using MIKE 21","authors":"K. Parvathy, D. Gopinath, V. Noujas, K. V. Thomas","doi":"10.1260/1759-3131.5.1.23","DOIUrl":"https://doi.org/10.1260/1759-3131.5.1.23","url":null,"abstract":"Nearshore wave transformation is a complex coastal process of shoaling, refraction, diffraction, reflection, and energy dissipation due to bed friction and breaking contributing variations in the wave height, period and direction. A well defined sediment cell of about 45 km extending from Kovalam headland to Varkala cliff which forms a part of Thiruvananthapuram coast along the southwest coast of India, is selected for the wave transformation studies. In the present study MIKE 21 Spectral Wave model (DHI, 2011) was used. The model simulates the growth, decay and transformation of wind generated waves and swells both in offshore and coastal areas. Providing MIKE 21 SW with a suitable bathymetry is essential for obtaining reliable results from the model. Usually the offshore bathymetry is derived from C-MAP, ETOPO, GEBCO etc. and the nearshore bathymetry is generated from close grid bathymetric surveys. In this study offshore bathymetry was generated from GEBCO-08 grid which is a freely available software with 30 arc (∼ 1 km) resolution. In the nearshore zone, surveyed close grid bathymetric data were used. The other inputs such as wave measurements and wind data provided in the model were from observations in Lakshadweep Sea. Model result is calibrated with field observations along this sector. The model has efficiently simulated the process of shoaling and refraction along the coast. The percentage of observed shoaling is 12.7% at a distance of 24 km from the shoreline at a depth of 70m and it was seen to be increasing to 27.9% when it reached around 2.4 km from the shore at a depth of 10m. The model result also shows that the wave is almost aligned parallel to the coast as wave approaches the coast. This model result can be used for further applications in designing along this coast.","PeriodicalId":105024,"journal":{"name":"The International Journal of Ocean and Climate Systems","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134397701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Statistical properties of the observed bi-variate ENSO time series (sea surface temperature within the Niño area 3.4 and the Southern Oscillation Index) from 1876 through 2005 are compared with respective properties of 46 CMIP5 models used in the historical experiment, one run per model. The models were found to exaggerate linear trend rates of SST; mean value and variance estimates have a large scatter, most probability densities are Gaussian, the shape of spectra is reproduced correctly in most cases though the spectra of simulated Southern Oscillation have a negative bias. Most estimates of coherence correctly reproduce the behavior of coherence between the observed SST and SOI that exceeds 0.9 at moderate frequencies. The average coherent spectrum of simulated SST is close to the “observed” coherent spectrum and has a negative bias in the SOI case. The results for the time domain require improvement; the frequency domain results are satisfactory.
{"title":"Validation of Numerical Climate Models for the El Niño-Southern Oscillation System","authors":"V. Privalsky, V. Yushkov","doi":"10.1260/1759-3131.5.1.1","DOIUrl":"https://doi.org/10.1260/1759-3131.5.1.1","url":null,"abstract":"Statistical properties of the observed bi-variate ENSO time series (sea surface temperature within the Niño area 3.4 and the Southern Oscillation Index) from 1876 through 2005 are compared with respective properties of 46 CMIP5 models used in the historical experiment, one run per model. The models were found to exaggerate linear trend rates of SST; mean value and variance estimates have a large scatter, most probability densities are Gaussian, the shape of spectra is reproduced correctly in most cases though the spectra of simulated Southern Oscillation have a negative bias. Most estimates of coherence correctly reproduce the behavior of coherence between the observed SST and SOI that exceeds 0.9 at moderate frequencies. The average coherent spectrum of simulated SST is close to the “observed” coherent spectrum and has a negative bias in the SOI case. The results for the time domain require improvement; the frequency domain results are satisfactory.","PeriodicalId":105024,"journal":{"name":"The International Journal of Ocean and Climate Systems","volume":"120 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116018456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：