scholarly journals The role of vertical shear on the horizontal oceanic dispersion

2015 ◽  
Vol 12 (5) ◽  
pp. 2073-2096
Author(s):  
A. S. Lanotte ◽  
R. Corrado ◽  
G. Lacorata ◽  
L. Palatella ◽  
C. Pizzigalli ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Vertical Velocity ◽  
Marine Biology ◽  
Pollutant Dispersion ◽  
Ocean Model ◽  
Three Dimensions ◽  
Vertical Shear ◽  
Time Variability ◽  
Horizontal Dispersion ◽  
Basin Scale

Abstract. The effect of vertical shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of South Mediterranean is investigated by means of observative and model data. In-situ current measurements reveal that vertical velocity gradients in the upper mixed layer decorrelate quite fast (∼ 1 day), whereas basin-scale ocean circulation models tend to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion simulated by an eddy-permitting ocean model, like, e.g., the Mediterranean Forecasting System, is mosty affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out; (2) poorly resolved time variability of vertical velocity profiles in the upper layer. For the case study we have analysed, we show that a suitable use of kinematic parameterisations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications.

scholarly journals Effects of vertical shear in modelling horizontal oceanic dispersion

Ocean Science ◽  
2016 ◽  
Vol 12 (1) ◽  
pp. 207-216 ◽  
Author(s):  
A. S. Lanotte ◽  
R. Corrado ◽  
L. Palatella ◽  
C. Pizzigalli ◽  
I. Schipa ◽  
...  
Keyword(s):  
Marine Biology ◽  
Mixing Layer ◽  
Pollutant Dispersion ◽  
Ocean Model ◽  
Three Dimensions ◽  
Vertical Shear ◽  
Time Variability ◽  
Horizontal Dispersion ◽  
Forecasting System ◽  
The Mediterranean

Abstract. The effect of vertical shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of the South Mediterranean is investigated by means of observation and model data. In situ current measurements reveal that vertical gradients of horizontal velocities in the upper mixing layer decorrelate quite fast ( ∼  1 day), whereas an eddy-permitting ocean model, such as the Mediterranean Forecasting System, tends to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion, simulated by the Mediterranean sea Forecasting System, is mostly affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out at scales close to the grid spacing; (2) poorly resolved time variability in the profiles of the horizontal velocities in the upper layer. For the case study we have analysed, we show that a suitable use of deterministic kinematic parametrizations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications.

scholarly journals A Closure for Internal Wave–Mean Flow Interaction. Part II: Wave Drag

2017 ◽  
Vol 47 (6) ◽  
pp. 1403-1412 ◽  
Author(s):  
Carsten Eden ◽  
Dirk Olbers
Keyword(s):  
Wave Propagation ◽  
Internal Wave ◽  
Ocean Circulation ◽  
Wave Drag ◽  
Ocean Model ◽  
Vertical Shear ◽  
Mean Flow ◽  
Flow Interaction ◽  
Two Dimensional Flow ◽  
Novel Concept

AbstractA novel concept for parameterizing internal wave–mean flow interaction in ocean circulation models is extended to an arbitrary two-dimensional flow with vertical shear. The concept is based on the description of the entire wave field by the wave-energy density in physical and wavenumber space and its prognostic computation by the radiative transfer equation integrated in wavenumber space. Energy compartments result for the horizontal direction of wave propagation as additional prognostic model variables, of which only four are taken here for simplicity. The mean flow is interpreted as residual velocities with respect to the wave activity. The effect of wave drag and energy exchange due to the vertical shear of the residual mean flow is then given simply by a vertical flux of momentum. This flux is related to the asymmetries in upward, downward, alongflow, and counterflow wave propagation described by the energy compartments. A numerical implementation in a realistic eddying ocean model shows that the wave drag effect is a significant sink of kinetic energy in the interior ocean.

scholarly journals MODELACIóN NUMÉRICA DE LA CIRCULACIÓN MARINA EN LAS BAHÍAS CALLAO y MIRAFLORES

2019 ◽  
pp. 59-66
Keyword(s):  
Ocean Circulation ◽  
Pollutant Dispersion ◽  
Circulation Pattern ◽  
Ocean Model ◽  
Ocean Dynamics ◽  
Coastal Morphology ◽  
Princeton Ocean Model ◽  
Tidal Propagation ◽  
Palabras Clave ◽  
San Marcos

MODELACIóN NUMÉRICA DE LA CIRCULACIÓN MARINA EN LAS BAHÍAS CALLAO y MIRAFLORES NUMERICAL MODELING OF CIRCULATION IN CALLAO AND MIRAFLORES BAYS Mirian Centeno, Emanuel Guzmán y Paúl García Grupo de Estudio de la Dinámica Marina, Ingeniería Mecánica de Fluidos, Universidad Nacional Mayor de San Marcos, Lima 01, Perú DOI: https://doi.org/10.33017/RevECIPeru2010.0009/ RESUMEN El presente trabajo consiste en estudiar a nivel superficial la circulación marina en las bahías del Callao y Miraflores, mediante el uso del modelo numérico Princeton Ocean Model conocido como POM, el cual es un conjunto de ecuaciones y parámetros que gobiernan la dinámica oceánica. El modelo POM se empleó con la finalidad de caracterizar el patrón de circulación en el área de estudio, analizando la influencia de los forzantes viento y marea (propagación del Norte) en la generación de corrientes marinas, así como los efectos que se producen a causa de la morfología costera y la presencia de la Isla; estos factores influyen en los resultados indicando una complejidad en las corrientes marinas, como la presencia de vórtices dentro de la bahía del Callao, así también la propagación de mareas se manifiestan en el área del puerto del Callao generando las corrientes de flujo y reflujo. Conociendo la circulación marina en las Bahías de Callao y Miraflores, se podrá realizar estudios posteriores de dispersión de contaminante, descargas residuales, derrames accidentales de sustancias, así también estudios de transporte de sedimentos aportados por la presencia de los ríos Rímac y Chillón. Palabras clave: Circulación marina, Princeton Ocean Model, Bahías del Callao y Miraflores ABSTRACT The present work is related to study the surface circulation in Callao and Miraflores bays using Princeton Ocean Model (POM) model, which is a set of equations and parameters that govern the ocean dynamics. POM was used to caracterize the circulation pattern in the study area, analyzing the main influence of wind stress and tide in the generation of currents and the effects occur because of the coastal morphology and the presence of the Island, these factors influence the results indicating a complexity in the ocean currents and the presence of vortices inside the bay of Callao, also tidal propagation manifests in the area of the port of Callao, generating currents ebb and flow. In this way, knowing the ocean circulation in the Callao and Miraflores bays, further studies can be made pollutant dispersion, wastewater discharges, accidental spills of substances, and also sediment transport studies produced by the presence of Rimac and Chillon rivers. Keywords: Marine Circulation, Princeton Ocean Model, Callao y Miraflores bays.

scholarly journals A Lagrangian Ocean Model for Climate Studies

Climate ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 41 ◽  
Author(s):  
Patrick Haertel
Keyword(s):  
Partial Differential Equations ◽  
Differential Equations ◽  
Ocean Circulation ◽  
Climate Models ◽  
Atmospheric Model ◽  
Ocean Model ◽  
Partial Differential ◽  
Mass Distributions ◽  
Global Atmospheric Model ◽  
Basin Scale

Most weather and climate models simulate circulations by numerically approximating a complex system of partial differential equations that describe fluid flow. These models also typically use one of a few standard methods to parameterize the effects of smaller-scale circulations such as convective plumes. This paper discusses the continued development of a radically different modeling approach. Rather than solving partial differential equations, the author’s Lagrangian models predict the motions of individual fluid parcels using ordinary differential equations. They also use a unique convective parameterization, in which the vertical positions of fluid parcels are rearranged to remove convective instability. Previously, a global atmospheric model and basin-scale ocean models were developed with this approach. In the present study, components of these models are combined to create a new global Lagrangian ocean model (GLOM), which will soon be coupled to a Lagrangian atmospheric model. The first simulations conducted with the GLOM examine the contribution of interior tracer mixing to ocean circulation, stratification, and water mass distributions, and they highlight several special model capabilities: (1) simulating ocean circulations without numerical diffusion of tracers; (2) modeling deep convective transports at low resolution; and (3) identifying the formation location of ocean water masses and water pathways.

scholarly journals Tracking the long-distance dispersal of marine organisms: sensitivity to ocean model resolution

2013 ◽  
Vol 10 (81) ◽  
pp. 20120979 ◽  
Author(s):  
Nathan F. Putman ◽  
Ruoying He
Keyword(s):  
Ocean Circulation ◽  
Circulation Model ◽  
Ocean Model ◽  
Marine Organisms ◽  
Model Output ◽  
Ocean Circulation Model ◽  
Time Step ◽  
Long Distance ◽  
Near Surface ◽  
Basin Scale

Ocean circulation models are widely used to simulate organism transport in the open sea, where challenges of directly tracking organisms across vast spatial and temporal scales are daunting. Many recent studies tout the use of ‘high-resolution’ models, which are forced with atmospheric data on the scale of several hours and integrated with a time step of several minutes or seconds. However, in many cases, the model's outputs that are used to simulate organism movement have been averaged to considerably coarser resolutions (e.g. monthly mean velocity fields). To examine the sensitivity of tracking results to ocean circulation model output resolution, we took the native model output of one of the most sophisticated ocean circulation models available, the Global Hybrid Coordinate Ocean Model, and averaged it to commonly implemented spatial and temporal resolutions in studies of basin-scale dispersal. Comparisons between simulated particle trajectories and in situ near-surface drifter trajectories indicated that ‘over averaging’ model output yields predictions inconsistent with observations. Further analyses focused on the dispersal of juvenile sea turtles indicate that very different inferences regarding the pelagic ecology of these animals are obtained depending on the resolution of model output. We conclude that physical processes occurring at the scale of days and tens of kilometres should be preserved in ocean circulation model output to realistically depict the movement marine organisms and the resulting ecological and evolutionary processes.

scholarly journals Wind-Driven Response of the Northern Indian Ocean to Climate Extremes*

2007 ◽  
Vol 20 (13) ◽  
pp. 2978-2993 ◽  
Author(s):  
Tommy G. Jensen
Keyword(s):  
Indian Ocean ◽  
Ocean Circulation ◽  
Bay Of Bengal ◽  
El Niño ◽  
Arabian Sea ◽  
El Nino ◽  
Ocean Model ◽  
La Niña ◽  
Northern Indian Ocean ◽  
La Nina

Abstract Composites of Florida State University winds (1970–99) for four different climate scenarios are used to force an Indian Ocean model. In addition to the mean climatology, the cases include La Niña, El Niño, and the Indian Ocean dipole (IOD). The differences in upper-ocean water mass exchanges between the Arabian Sea and the Bay of Bengal are investigated and show that, during El Niño and IOD years, the average clockwise Indian Ocean circulation is intensified, while it is weakened during La Niña years. As a consequence, high-salinity water export from the Arabian Sea into the Bay of Bengal is enhanced during El Niño and IOD years, while transport of low-salinity waters from the Bay of Bengal into the Arabian Sea is enhanced during La Niña years. This provides a venue for interannual salinity variations in the northern Indian Ocean.

Quantifying the Predictive Skill in Long-Range Forecasting. Part II: Model Error in Coarse-Grained Markov Models with Application to Ocean-Circulation Regimes

2012 ◽  
Vol 25 (6) ◽  
pp. 1814-1826 ◽  
Author(s):  
Dimitrios Giannakis ◽  
Andrew J. Majda
Keyword(s):  
Long Range ◽  
Ocean Circulation ◽  
Climate Models ◽  
Markov Models ◽  
Low Frequency ◽  
Model Error ◽  
Ocean Model ◽  
Coarse Grained ◽  
Predictive Skill ◽  
Relaxation To Equilibrium

Abstract An information-theoretic framework is developed to assess the predictive skill and model error in imperfect climate models for long-range forecasting. Here, of key importance is a climate equilibrium consistency test for detecting false predictive skill, as well as an analogous criterion describing model error during relaxation to equilibrium. Climate equilibrium consistency enforces the requirement that long-range forecasting models should reproduce the climatology of prediction observables with high fidelity. If a model meets both climate consistency and the analogous criterion describing model error during relaxation to equilibrium, then relative entropy can be used as an unbiased superensemble measure of the model’s skill in long-range coarse-grained forecasts. As an application, the authors investigate the error in modeling regime transitions in a 1.5-layer ocean model as a Markov process and identify models that are strongly persistent but their predictive skill is false. The general techniques developed here are also useful for estimating predictive skill with model error for Markov models of low-frequency atmospheric regimes.

scholarly journals Dynamic Downscaling of the Impact of Climate Change on the Ocean Circulation in the Galápagos Archipelago

2013 ◽  
Vol 2013 ◽  
pp. 1-18 ◽  
Author(s):  
Yanyun Liu ◽  
Lian Xie ◽  
John M. Morrison ◽  
Daniel Kamykowski
Keyword(s):  
Climate Change ◽  
Ocean Circulation ◽  
Global Climate Change ◽  
Climate Model ◽  
Global Climate ◽  
Ocean Model ◽  
Reanalysis Dataset ◽  
Equatorial Undercurrent ◽  
Galapagos Archipelago ◽  
The Impact

The regional impact of global climate change on the ocean circulation around the Galápagos Archipelago is studied using the Hybrid Coordinate Ocean Model (HYCOM) configured for a four-level nested domain system. The modeling system is validated and calibrated using daily atmospheric forcing derived from the NCEP/NCAR reanalysis dataset from 1951 to 2007. The potential impact of future anthropogenic global warming (AGW) in the Galápagos region is examined using the calibrated HYCOM with forcing derived from the IPCC-AR4 climate model. Results show that although the oceanic variability in the entire Galápagos region is significantly affected by global climate change, the degree of such effects is inhomogeneous across the region. The upwelling region to the west of the Isabella Island shows relatively slower warming trends compared to the eastern Galápagos region. Diagnostic analysis suggests that the variability in the western Galápagos upwelling region is affected mainly by equatorial undercurrent (EUC) and Panama currents, while the central/east Galápagos is predominantly affected by both Peru and EUC currents. The inhomogeneous responses in different regions of the Galápagos Archipelago to future AGW can be explained by the incoherent changes of the various current systems in the Galápagos region as a result of global climate change.

scholarly journals Effects of Ocean Biology on the Penetrative Radiation in a Coupled Climate Model

2006 ◽  
Vol 19 (16) ◽  
pp. 3973-3987 ◽  
Author(s):  
Patrick Wetzel ◽  
Ernst Maier-Reimer ◽  
Michael Botzet ◽  
Johann Jungclaus ◽  
Noel Keenlyside ◽  
...  
Keyword(s):  
Seasonal Cycle ◽  
Marine Biology ◽  
Climate Model ◽  
Global Climate ◽  
Ocean Model ◽  
Equatorial Pacific ◽  
Shortwave Radiation ◽  
Upper Ocean ◽  
Biogeochemical Model ◽  
Coupled Climate Model

Abstract The influence of phytoplankton on the seasonal cycle and the mean global climate is investigated in a fully coupled climate model. The control experiment uses a fixed attenuation depth for shortwave radiation, while the attenuation depth in the experiment with biology is derived from phytoplankton concentrations simulated with a marine biogeochemical model coupled online to the ocean model. Some of the changes in the upper ocean are similar to the results from previous studies that did not use interactive atmospheres, for example, amplification of the seasonal cycle; warming in upwelling regions, such as the equatorial Pacific and the Arabian Sea; and reduction in sea ice cover in the high latitudes. In addition, positive feedbacks within the climate system cause a global shift of the seasonal cycle. The onset of spring is about 2 weeks earlier, which results in a more realistic representation of the seasons. Feedback mechanisms, such as increased wind stress and changes in the shortwave radiation, lead to significant warming in the midlatitudes in summer and to seasonal modifications of the overall warming in the equatorial Pacific. Temperature changes also occur over land where they are sometimes even larger than over the ocean. In the equatorial Pacific, the strength of interannual SST variability is reduced by about 10%–15% and phase locking to the annual cycle is improved. The ENSO spectral peak is broader than in the experiment without biology and the dominant ENSO period is increased to around 5 yr. Also the skewness of ENSO variability is slightly improved. All of these changes lead to the conclusion that the influence of marine biology on the radiative budget of the upper ocean should be considered in detailed simulations of the earth’s climate.

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