MyOcean products in the CYCOFOS Decision Support System for Marine Safety
The MyOcean marine core service, implementing the GMES objectives is composed among other regiona... more The MyOcean marine core service, implementing the GMES objectives is composed among other regional forecasting centres by the Mediterranean, Black Sea and Baltic Sea ones. These centres, provide to the intermediate and to the Member States national marine services, as well to the end-users, forecasting products for sea currents, temperature, salinity and sea level. The MyOcean regional products in the Mediterranean are used by the CYCOFOS upgraded hydro-dynamical modules for hierarchically high resolution downscaled forecasts in the Levantine and its sub-basins. The MyOcean regional and CYCOFOS downscaled forecasting products are used for downstream services, leading to the establishment of a Decision Support System for marine safety in the European’s seas. The CYCOFOS DESS downstream service provide: a) short, 24 hours forward and backward predictions of oil spills primary in the Mediterranean and secondary upon request in the Black Sea and the Baltic Sea, using ASAR satellite imag...
The pan-European capacity for the Ocean Monitoring and Forecasting (MyOcean) Marine Core Service,... more The pan-European capacity for the Ocean Monitoring and Forecasting (MyOcean) Marine Core Service, implementing the Global Monitoring for Environment and Security (GMES) objectives, targets the provision of ocean state observations from various platforms and analysis and forecasting products to assist, among other downscaling activities, the needs of the operational response to marine safety, particularly concerning oil spills. The MEDSLIK oil spill and trajectory prediction system makes use of the MyOcean regional and Cyprus Coastal Ocean Forecasting and Observing System (CYCOFOS) downscaled forecasting products for operational application in the Mediterranean and pre-operational use in the Black Sea. Advanced Synthetic Aperture Radar (ASAR) satellite remote sensing images from the European Space Agency (ESA) and European Maritime Safety Agency CleanSeaNet (EMSA-CSN) provide the means for routine monitoring of the southern European seas for the detection of illegal oil discharges. MED-SLIK offers various ways, to be described in this paper, of coupling the MyOcean forecasting data with ASAR images to provide both forecasts and hindcasts for such remotely observed oil slicks. The main concern will be the drift of the oil slick and also, in the case of the forecast mode, its diffusive spreading, although some attempt is also made to estimate the changes in the state of the oil. The successful link of the satellite-detected oil slicks with their operational predictions using the MyOcean products contributes to the operational response chain and the strengthening of maritime safety for accidental or illegal spills, in implementation of the Mediterranean Decision Support System for Marine Safety (MEDESS-4MS) regarding oil spills.
Sub-regional forecasting and observing system in the eastern Mediterranean Levantine basin: the Cyprus coastal ocean forecasting and observing system (CYCOFOS)
In this work sensitivity experiments to the coupled MFS (currents) and MEDSLIK (oil spill) input ... more In this work sensitivity experiments to the coupled MFS (currents) and MEDSLIK (oil spill) input parameters will be shown and results w ill be compared with observations. In these experiments the drift angle, the drift factor , the currents depth, the type of oil, horizontal diffusivity and the horizontal and tempo ral current resolution were changed.
The hydrodynamical models of the Gulf developed at KFUPM Research Institute are briefly described... more The hydrodynamical models of the Gulf developed at KFUPM Research Institute are briefly described. The models are used to compute the flows in the Gulf driven by density gradient using the two sets of data collected on Legs 1 and 6 of the Mt Mitchell cruise. The two flows are compared with one another, with the result of a similar computation using the 1977 Atlantis H data and with computations of the flow driven by the prevailing wind. The combined residual flow due to wind and density gradient is found and compared to empirical estimates of the residual flow derived from ship-drift reports. The accuracy of the models is tested using the computed and observed water velocities at some of the current meters deployed during the cruise.
MOON (Mediterranean Operational Oceanography Network http://www.moon-oceanforecasting.eu) provide... more MOON (Mediterranean Operational Oceanography Network http://www.moon-oceanforecasting.eu) provides near-real-time information on oil-spill detection (ocean color and SAR) and predictions [ocean forecasts (MFS and CYCOFOS) and oil-spill predictions (MEDSLIK)]. We employ this system to study the Lebanese oil-pollution crisis in summer 2006 and thus to assist regional and local decision makers in Europe, regionally and locally. The MEDSLIK oil-spill predictions obtained using CYCOFOS high-resolution ocean fields are compared with those obtained using lower-resolution MFS hydrodynamics, and both are validated against satellite observations. The predicted beached oil distributions along the Lebanese and Syrian coasts are compared with in situ observations. The oil-spill predictions are able to simulate the northward movement of the oil spill, with the CYCO-FOS predictions being in better agreement with satellite observations. Among the free MEDSLIK parameters tested in the sensitivity experiments, the drift factor appears to be the most relevant to improve the quality of the results.
Van der Pol's equation with damping and time delay
Journal of Sound and Vibration, 1976
... This paper is concerned with the oscillations of an electronic circuit for which the governin... more ... This paper is concerned with the oscillations of an electronic circuit for which the governingequation is a generalization of ... equation (4) can easily be reduced to this standard form by means of the usual method of VAN DER POL'S EQUATION WITH DELAY 107 variation of ...
International Journal of Engineering Science, 1985
Using an asymptotic theory of nonlinear Rayleigh waves previously developed, numerical solutions ... more Using an asymptotic theory of nonlinear Rayleigh waves previously developed, numerical solutions are obtained for the variation with distance of the amplitudes of the higher harmonics in an initially sinusoidal wave. The two components of the particle velocity on the free surface are calculated and it is found that after a finite distance a shock develops in the form of a discontinuity in the horizontal velocity component.
The processes of transport, diffusion and transformation of surface oil in seawater can be simula... more The processes of transport, diffusion and transformation of surface oil in seawater can be simulated using a Lagrangian model formalism coupled with Eulerian circulation models. This paper describes the formalism and the conceptual assumptions of a Lagrangian marine surface oil slick numerical model and rewrites the constitutive equations in a modern mathematical framework. The Lagrangian numerical representation of the oil slick requires three different state variables: the slick, the particle and the structural state variables. Transformation processes (evaporation, spreading, dispersion and coastal adhesion) act on the slick state variables, while particle variables are used to model the transport and diffusion processes. The slick and particle variables are recombined together to compute the oil concentration in water, a structural state variable. The mathematical and numerical formulation of oil transport, diffusion and transformation processes described in this paper, together with the many simplifying hypothesis and parameterizations, form the basis of a new, open source Lagrangian surface oil spill model, the so-called MEDSLIK-II, based on its precursor MEDSLIK (Lardner et al., 1998, 2006; Zodiatis et al., 2008a). Part 2 of this paper describes the applications of the model to oil spill simulations that allow the validation of the model results and the study of the sensitivity of the simulated oil slick to different model numerical parameterizations.
A computational algorithm is proposed for steady oceanographic flows in which the two-dimensional... more A computational algorithm is proposed for steady oceanographic flows in which the two-dimensional shallow-water equations are coupled to a separate integration in the vertical direction. The algorithm is much more efficient than the conventional three-dimensional schemes. For a simple test model the results agree well with previous results published by Davies and Owen. 1
Finite difference model for tidal flows in the Arabian Gulf
Computers & Mathematics with Applications, 1982
A two-dimensional hydrodynamical model for tidal flows in the Arabian Gulf is developed. The mode... more A two-dimensional hydrodynamical model for tidal flows in the Arabian Gulf is developed. The model uses variable mesh-sizes to handle a more detailed tidal current filed in selected sub-regions. In this study, a three-block model scheme is developed in which the deep ...
A computational algorithm is proposed for the solution of the hydrodynamical equations appropriat... more A computational algorithm is proposed for the solution of the hydrodynamical equations appropriate for motions in shallow seas and estuaries. The surface elevation and depth-averaged velocity components are first computed using one of the standard two-dimensional algorithms for the solution of the shallow-water equations. These values are then used to compute the vertical profile of the velocity field by solving the two horizontal momentum equations. These equations form a coupled parabolic system, and a generalized Crank-Nicholson scheme is developed to solve them. In the case of constant eddy viscosity this scheme can be shown to be unconditionally stable, so the only stability restriction is the usual CFL condition on the shallow-water equations. Thus the time step is limited only in terms of the horizontal grid spacing, not by the vertical spacing. The algorithm is tested on a model problem previously used by Davies and Owen 1 involving the development of circulation in a rectangular sea under the influence of a constant surface wind-shear. The velocity profiles at various times are presented, and the final steady-state flow agrees very well with that computed by Davies and Owen. For constant eddy-viscosity the complete three-dimensional computation is only twice as slow as the two-dimensional computation that forms part of it.
MyOcean products in the CYCOFOS Decision Support System for Marine Safety
The MyOcean marine core service, implementing the GMES objectives is composed among other regiona... more The MyOcean marine core service, implementing the GMES objectives is composed among other regional forecasting centres by the Mediterranean, Black Sea and Baltic Sea ones. These centres, provide to the intermediate and to the Member States national marine services, as well to the end-users, forecasting products for sea currents, temperature, salinity and sea level. The MyOcean regional products in the Mediterranean are used by the CYCOFOS upgraded hydro-dynamical modules for hierarchically high resolution downscaled forecasts in the Levantine and its sub-basins. The MyOcean regional and CYCOFOS downscaled forecasting products are used for downstream services, leading to the establishment of a Decision Support System for marine safety in the European’s seas. The CYCOFOS DESS downstream service provide: a) short, 24 hours forward and backward predictions of oil spills primary in the Mediterranean and secondary upon request in the Black Sea and the Baltic Sea, using ASAR satellite imag...
The pan-European capacity for the Ocean Monitoring and Forecasting (MyOcean) Marine Core Service,... more The pan-European capacity for the Ocean Monitoring and Forecasting (MyOcean) Marine Core Service, implementing the Global Monitoring for Environment and Security (GMES) objectives, targets the provision of ocean state observations from various platforms and analysis and forecasting products to assist, among other downscaling activities, the needs of the operational response to marine safety, particularly concerning oil spills. The MEDSLIK oil spill and trajectory prediction system makes use of the MyOcean regional and Cyprus Coastal Ocean Forecasting and Observing System (CYCOFOS) downscaled forecasting products for operational application in the Mediterranean and pre-operational use in the Black Sea. Advanced Synthetic Aperture Radar (ASAR) satellite remote sensing images from the European Space Agency (ESA) and European Maritime Safety Agency CleanSeaNet (EMSA-CSN) provide the means for routine monitoring of the southern European seas for the detection of illegal oil discharges. MED-SLIK offers various ways, to be described in this paper, of coupling the MyOcean forecasting data with ASAR images to provide both forecasts and hindcasts for such remotely observed oil slicks. The main concern will be the drift of the oil slick and also, in the case of the forecast mode, its diffusive spreading, although some attempt is also made to estimate the changes in the state of the oil. The successful link of the satellite-detected oil slicks with their operational predictions using the MyOcean products contributes to the operational response chain and the strengthening of maritime safety for accidental or illegal spills, in implementation of the Mediterranean Decision Support System for Marine Safety (MEDESS-4MS) regarding oil spills.
Sub-regional forecasting and observing system in the eastern Mediterranean Levantine basin: the Cyprus coastal ocean forecasting and observing system (CYCOFOS)
In this work sensitivity experiments to the coupled MFS (currents) and MEDSLIK (oil spill) input ... more In this work sensitivity experiments to the coupled MFS (currents) and MEDSLIK (oil spill) input parameters will be shown and results w ill be compared with observations. In these experiments the drift angle, the drift factor , the currents depth, the type of oil, horizontal diffusivity and the horizontal and tempo ral current resolution were changed.
The hydrodynamical models of the Gulf developed at KFUPM Research Institute are briefly described... more The hydrodynamical models of the Gulf developed at KFUPM Research Institute are briefly described. The models are used to compute the flows in the Gulf driven by density gradient using the two sets of data collected on Legs 1 and 6 of the Mt Mitchell cruise. The two flows are compared with one another, with the result of a similar computation using the 1977 Atlantis H data and with computations of the flow driven by the prevailing wind. The combined residual flow due to wind and density gradient is found and compared to empirical estimates of the residual flow derived from ship-drift reports. The accuracy of the models is tested using the computed and observed water velocities at some of the current meters deployed during the cruise.
MOON (Mediterranean Operational Oceanography Network http://www.moon-oceanforecasting.eu) provide... more MOON (Mediterranean Operational Oceanography Network http://www.moon-oceanforecasting.eu) provides near-real-time information on oil-spill detection (ocean color and SAR) and predictions [ocean forecasts (MFS and CYCOFOS) and oil-spill predictions (MEDSLIK)]. We employ this system to study the Lebanese oil-pollution crisis in summer 2006 and thus to assist regional and local decision makers in Europe, regionally and locally. The MEDSLIK oil-spill predictions obtained using CYCOFOS high-resolution ocean fields are compared with those obtained using lower-resolution MFS hydrodynamics, and both are validated against satellite observations. The predicted beached oil distributions along the Lebanese and Syrian coasts are compared with in situ observations. The oil-spill predictions are able to simulate the northward movement of the oil spill, with the CYCO-FOS predictions being in better agreement with satellite observations. Among the free MEDSLIK parameters tested in the sensitivity experiments, the drift factor appears to be the most relevant to improve the quality of the results.
Van der Pol's equation with damping and time delay
Journal of Sound and Vibration, 1976
... This paper is concerned with the oscillations of an electronic circuit for which the governin... more ... This paper is concerned with the oscillations of an electronic circuit for which the governingequation is a generalization of ... equation (4) can easily be reduced to this standard form by means of the usual method of VAN DER POL'S EQUATION WITH DELAY 107 variation of ...
International Journal of Engineering Science, 1985
Using an asymptotic theory of nonlinear Rayleigh waves previously developed, numerical solutions ... more Using an asymptotic theory of nonlinear Rayleigh waves previously developed, numerical solutions are obtained for the variation with distance of the amplitudes of the higher harmonics in an initially sinusoidal wave. The two components of the particle velocity on the free surface are calculated and it is found that after a finite distance a shock develops in the form of a discontinuity in the horizontal velocity component.
The processes of transport, diffusion and transformation of surface oil in seawater can be simula... more The processes of transport, diffusion and transformation of surface oil in seawater can be simulated using a Lagrangian model formalism coupled with Eulerian circulation models. This paper describes the formalism and the conceptual assumptions of a Lagrangian marine surface oil slick numerical model and rewrites the constitutive equations in a modern mathematical framework. The Lagrangian numerical representation of the oil slick requires three different state variables: the slick, the particle and the structural state variables. Transformation processes (evaporation, spreading, dispersion and coastal adhesion) act on the slick state variables, while particle variables are used to model the transport and diffusion processes. The slick and particle variables are recombined together to compute the oil concentration in water, a structural state variable. The mathematical and numerical formulation of oil transport, diffusion and transformation processes described in this paper, together with the many simplifying hypothesis and parameterizations, form the basis of a new, open source Lagrangian surface oil spill model, the so-called MEDSLIK-II, based on its precursor MEDSLIK (Lardner et al., 1998, 2006; Zodiatis et al., 2008a). Part 2 of this paper describes the applications of the model to oil spill simulations that allow the validation of the model results and the study of the sensitivity of the simulated oil slick to different model numerical parameterizations.
A computational algorithm is proposed for steady oceanographic flows in which the two-dimensional... more A computational algorithm is proposed for steady oceanographic flows in which the two-dimensional shallow-water equations are coupled to a separate integration in the vertical direction. The algorithm is much more efficient than the conventional three-dimensional schemes. For a simple test model the results agree well with previous results published by Davies and Owen. 1
Finite difference model for tidal flows in the Arabian Gulf
Computers & Mathematics with Applications, 1982
A two-dimensional hydrodynamical model for tidal flows in the Arabian Gulf is developed. The mode... more A two-dimensional hydrodynamical model for tidal flows in the Arabian Gulf is developed. The model uses variable mesh-sizes to handle a more detailed tidal current filed in selected sub-regions. In this study, a three-block model scheme is developed in which the deep ...
A computational algorithm is proposed for the solution of the hydrodynamical equations appropriat... more A computational algorithm is proposed for the solution of the hydrodynamical equations appropriate for motions in shallow seas and estuaries. The surface elevation and depth-averaged velocity components are first computed using one of the standard two-dimensional algorithms for the solution of the shallow-water equations. These values are then used to compute the vertical profile of the velocity field by solving the two horizontal momentum equations. These equations form a coupled parabolic system, and a generalized Crank-Nicholson scheme is developed to solve them. In the case of constant eddy viscosity this scheme can be shown to be unconditionally stable, so the only stability restriction is the usual CFL condition on the shallow-water equations. Thus the time step is limited only in terms of the horizontal grid spacing, not by the vertical spacing. The algorithm is tested on a model problem previously used by Davies and Owen 1 involving the development of circulation in a rectangular sea under the influence of a constant surface wind-shear. The velocity profiles at various times are presented, and the final steady-state flow agrees very well with that computed by Davies and Owen. For constant eddy-viscosity the complete three-dimensional computation is only twice as slow as the two-dimensional computation that forms part of it.
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Papers by R. Lardner