scholarly journals The analysis of large-scale turbulence characteristics in the Indonesian seas derived from a regional model based on the Princeton Ocean Model

2012 ◽  
Vol 9 (1) ◽  
pp. 63-103
Author(s):  
K. O'Driscoll ◽  
V. Kamenkovich
Keyword(s):  
Kinetic Energy ◽  
Ocean Circulation ◽  
Regional Model ◽  
Ocean Model ◽  
Princeton Ocean Model ◽  
Turbulence Characteristics ◽  
Indonesian Seas ◽  
The North ◽  
Closure Scheme ◽  
Mixing Coefficients

Abstract. The analysis is presented of the distribution of deep ocean turbulence characteristics on the horizontal scale of order 100 km in the vicinity of the Lifamatola Sill, from the Southern Maluku Sea (north of the sill) to the Seram Sea (south of the sill). The turbulence characteristics were calculated with a regional model of the Indonesian seas circulation based on the Princeton Ocean Model (POM), incorporating the Mellor-Yamada turbulence closure scheme. The analysis has been carried out for the entire Indonesian seas region, including areas around important topographic features, such as the Lifamatola Sill, the North Sangihe Ridge, the Dewakang Sill and the North and South Halmahera Sea Sills. To illustrate results of application of the Mellor-Yamada closure scheme we have focused on the description of features of turbulence characteristics across the Lifamatola Sill because dynamically this region is very important and some estimates of mixing coefficients in this area are available. As is well known, the POM model output provides both dynamical (depth-integrated and 3-D velocities, temperature, salinity, and sea-surface-height) and turbulence characteristics (kinetic energy and master scale of turbulence, mixing coefficients of momentum, temperature and salinity, etc.). As a rule, the analysis of POM modeling results has been restricted to the study of corresponding dynamical characteristics, however the study of turbulence characteristics is essential to understanding the dynamics of the ocean circulation as well. Due to the absence of direct measurements of turbulence characteristics in the analyzed area, we argued the validity of the simulated characteristics in the light of their compatibility with some general principles. Thus, along these lines, vertical profiles of across-the-sill velocities, twice the kinetic energy of turbulence, turbulence length scale, the separate terms in the equation of kinetic energy of turbulence, the Richardson number, and finally coefficients of mixing of momentum and temperature and salinity are discussed. Average values of the vertical mixing coefficient compare well with indirect estimates previously made from diagnostic calculations based on Munk's model.

scholarly journals The analysis of large-scale turbulence characteristics in the Indonesian seas derived from a regional model based on the Princeton Ocean Model

Ocean Science ◽  
2012 ◽  
Vol 8 (4) ◽  
pp. 615-631
Author(s):  
K. O'Driscoll ◽  
V. Kamenkovich
Keyword(s):  
Large Scale ◽  
Regional Model ◽  
Ocean Model ◽  
Velocity Shear ◽  
Princeton Ocean Model ◽  
Turbulence Characteristics ◽  
Indonesian Seas ◽  
The North ◽  
Basin Scale ◽  
Mixing Coefficients

Abstract. Turbulence characteristics in the Indonesian seas on the horizontal scale of order of 100 km were calculated with a regional model of the Indonesian seas circulation in the area based on the Princeton Ocean Model (POM). As is well known, the POM incorporates the Mellor–Yamada turbulence closure scheme. The calculated characteristics are: twice the turbulence kinetic energy per unit mass, q2; the turbulence master scale, ℓ; mixing coefficients of momentum, KM; and temperature and salinity, KH; etc. The analyzed turbulence has been generated essentially by the shear of large-scale ocean currents and by the large-scale wind turbulence. We focused on the analysis of turbulence around important topographic features, such as the Lifamatola Sill, the North Sangihe Ridge, the Dewakang Sill, and the North and South Halmahera Sea Sills. In general, the structure of turbulence characteristics in these regions turned out to be similar. For this reason, we have carried out a detailed analysis of the Lifamatola Sill region because dynamically this region is very important and some estimates of mixing coefficients in this area are available. Briefly, the main results are as follows. The distribution of q2 is quite adequately reproduced by the model. To the north of the Lifamatola Sill (in the Maluku Sea) and to the south of the Sill (in the Seram Sea), large values of q2 occur in the deep layer extending several hundred meters above the bottom. The observed increase of q2 near the very bottom is probably due to the increase of velocity shear and the corresponding shear production of q2 very close to the bottom. The turbulence master scale, ℓ, was found to be constant in the main depth of the ocean, while ℓ rapidly decreases close to the bottom, as one would expect. However, in deep profiles away from the sill, the effect of topography results in the ℓ structure being unreasonably complicated as one moves towards the bottom. Values of 15 to 20 × 10−4 m2 s−1 were obtained for KM and KH in deep water in the vicinity of the Lifamatola Sill. These estimates agree well with basin-scale averaged values of 13.3 × 10−4 m2 s−1 found diagnostically for KH in the deep Banda and Seram Seas (Gordon et al., 2003) and a value of 9.0 × 10−4 m2 s−1 found diagnostically for KH for the deep Banda Sea system (van Aken et al., 1988). The somewhat higher simulated values can be explained by the presence of steep topography around the sill.

Why Does Western Indian Ocean Circulation Connectivity Matter?

2021 ◽  
Author(s):  
Stephen Kelly ◽  
Ekaterina Popova ◽  
Zoe Jacobs
Keyword(s):  
Indian Ocean ◽  
Ocean Circulation ◽  
Western Indian Ocean ◽  
Ocean Model ◽  
Marine Conservation ◽  
Surface Currents ◽  
Resource Exploitation ◽  
Larval Stages ◽  
The North ◽  
Particle Tracking Method

<p>Marine circulation connectivity describes the pathways and timescales over which spatially separated parts of the ocean are connected by oceanic currents. In the Western Indian Ocean (WIO), these pathways and associated timescales are characterised by pronounced seasonal and interannual variability, including monsoon-driven reversal of surface currents in the northern part of the basin.</p><p>Understanding the connectivity timescales in the WIO – and their variability – is important for a multitude of reasons. Ecological connectivity between coral reefs is necessary to maintain their biodiversity, understanding downstream connectivity from marine resource exploitation sites is important to understand which areas are likely to be affected, and circulation connectivity is a key concern when designing marine conservation measures. For example, establishing an effective network of marine protected areas (MPAs) requires that they are connected on ecologically relevant timescales (e.g. the duration of species’ pelagic larval stages), but gaps in the existing MPA network mean that decisions need to be undertaken about which areas to prioritise for future protection. Therefore, knowledge of the advective pathways connecting the WIO over these timescales is essential for effective management of the region.</p><p>Here, a Lagrangian particle tracking method is used in conjunction with a 1/12° resolution ocean model to elucidate the advective pathways mediated by major surface currents in the WIO. Model experiments are performed with virtual particles released into several major WIO currents and tracked for 100 days, and the resulting trajectories are analysed. Significant variability was found, with advective pathways and timescales sensitive to both season and year of release. The main differences are associated with the different monsoon regimes driving changes in connectivity timescales, and reversing direction of advective pathways in the north of the WIO. In addition to this seasonal variability, interannual changes are explored. Case studies of anomalous connectivity pathways / timescales are presented and discussed in the context of extremes in forcing and larger scale variability, including the Indian Ocean Dipole.  </p>

scholarly journals Millennial Variability in an Idealized Ocean Model: Predicting the AMOC Regime Shifts

2014 ◽  
Vol 27 (10) ◽  
pp. 3551-3564 ◽  
Author(s):  
Florian Sévellec ◽  
Alexey V. Fedorov
Keyword(s):  
Ocean Circulation ◽  
Salient Feature ◽  
Ocean Model ◽  
Meridional Overturning Circulation ◽  
Overturning Circulation ◽  
Small Perturbations ◽  
Ocean Stratification ◽  
The North ◽  
Chaotic Model ◽  
Meridional Overturning

Abstract A salient feature of paleorecords of the last glacial interval in the North Atlantic is pronounced millennial variability, commonly known as Dansgaard–Oeschger events. It is believed that these events are related to variations in the Atlantic meridional overturning circulation and heat transport. Here, the authors formulate a new low-order model, based on the Howard–Malkus loop representation of ocean circulation, capable of reproducing millennial variability and its chaotic dynamics realistically. It is shown that even in this chaotic model changes in the state of the meridional overturning circulation are predictable. Accordingly, the authors define two predictive indices which give accurate predictions for the time the circulation should remain in the on phase and then stay in the subsequent off phase. These indices depend mainly on ocean stratification and describe the linear growth of small perturbations in the system. Thus, monitoring particular indices of the ocean state could help predict a potential shutdown of the overturning circulation.

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 model study of the seasonal and long–term North Atlantic surface <i>p</i>CO<sub>2</sub> variability

2012 ◽  
Vol 9 (3) ◽  
pp. 907-923 ◽  
Author(s):  
J. F. Tjiputra ◽  
A. Olsen ◽  
K. Assmann ◽  
B. Pfeil ◽  
C. Heinze
Keyword(s):  
Heat Flux ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Dissolved Inorganic Carbon ◽  
Ocean Model ◽  
Surface Ocean ◽  
The North ◽  
Increasing Trend ◽  
The North Atlantic

Abstract. A coupled biogeochemical-physical ocean model is used to study the seasonal and long–term variations of surface pCO2 in the North Atlantic Ocean. The model agrees well with recent underway pCO2 observations from the Surface Ocean CO2 Atlas (SOCAT) in various locations in the North Atlantic. Some of the distinct seasonal cycles observed in different parts of the North Atlantic are well reproduced by the model. In most regions except the subpolar domain, recent observed trends in pCO2 and air–sea carbon fluxes are also simulated by the model. Over the longer period between 1960–2008, the primary mode of surface pCO2 variability is dominated by the increasing trend associated with the invasion of anthropogenic CO2 into the ocean. We show that the spatial variability of this dominant increasing trend, to first order, can be explained by the surface ocean circulation and air–sea heat flux patterns. Regions with large surface mass transport and negative air–sea heat flux have the tendency to maintain lower surface pCO2. Regions of surface convergence and mean positive air–sea heat flux such as the subtropical gyre and the western subpolar gyre have a higher long–term surface pCO2 mean. The North Atlantic Oscillation (NAO) plays a major role in controlling the variability occurring at interannual to decadal time scales. The NAO predominantly influences surface pCO2 in the North Atlantic by changing the physical properties of the North Atlantic water masses, particularly by perturbing the temperature and dissolved inorganic carbon in the surface ocean. We show that present underway sea surface pCO2 observations are valuable for both calibrating the model, as well as for improving our understanding of the regionally heterogeneous variability of surface pCO2. In addition, they can be important for detecting any long term change in the regional carbon cycle due to ongoing climate change.

scholarly journals MOMSO 1.0 - a near-global, coupled biogeochemical ocean-circulation model configuration with realistic eddy kinetic energy in the Southern Ocean

2019 ◽  
Author(s):  
Heiner Dietze ◽  
Ulrike Löptien ◽  
Julia Getzlaff
Keyword(s):  
Kinetic Energy ◽  
Southern Ocean ◽  
Ocean Circulation ◽  
Computational Cost ◽  
Circulation Model ◽  
Ocean Model ◽  
Eddy Kinetic Energy ◽  
Ocean Circulation Model ◽  
Model Configuration ◽  
Modular Ocean Model

Abstract. We present a new near-global coupled biogeochemical ocean-circulation model configuration. The configuration features a horizontal discretization with a grid spacing of less than 11 km in the Southern Ocean and gradually coarsens in meridional direction to more than 200 km at 64° N where the model is bounded by a solid wall. The underlying code framework is GFDL's Modular Ocean Model coupled to the Biology Light Iron Nutrients and Gasses (BLING) ecosystem model of Galbraith et al. (2010). The configuration is cutting-edge in that it features both a relatively equilibrated oceanic carbon inventory and a realistic representation of eddy kinetic energy – a combination that has, to-date, been precluded by prohibitive computational cost. Results from a simulation with climatological forcing and a sensitivity experiment with increasing winds suggest that the configuration is suited to explore Southern Ocean Carbon uptake dynamics on decadal timescales. Further, the fidelity of simulated bottom water temperatures off and on the Antarctic Shelf suggest that the configuration may be used to provide boundary conditions to ice-sheet models. The configuration is dubbed MOMSO a Modular Ocean Model Southern Ocean configuration.

Eddies and their energetics in the Bay of Bengal

2020 ◽  
Author(s):  
Navin Chandra ◽  
Vimlesh Pant
Keyword(s):  
Kinetic Energy ◽  
Ocean Circulation ◽  
Bay Of Bengal ◽  
Cold Water ◽  
Thermal Structure ◽  
Thermodynamic Characteristics ◽  
Surface Current ◽  
Ocean Model ◽  
Coastal Current ◽  
Current Pattern

&lt;p&gt;Eddies are integral part of ocean circulation. They play an important role in energy transfer. The surface kinetic energy in eddies can be ten times higher than the energy of the current through which these are generated. Eddies influence the thermodynamic characteristics of the upper-ocean. Oceanic eddies trap and transport hot (cold) water in the core of an anticyclonic (cyclonic) eddy. Therefore, these eddies can modify the thermal structure by the advection of temperature anomalies and its subsequent mixing. Generation of eddies takes place mainly due to the baroclinic instability of the ocean. However, some of the eddies may form due to coastal and bathymetrical geometry. The Bay of Bengal (BoB) is an enclosed basin in the northern Indian Ocean (IO). The BoB exhibits unique physical and dynamical properties due to surplus low-saline waters and shallow mixed layer. It observes seasonal variation of wind and changes in the surface current pattern. Major rivers originating from the Himalayan glaciers drain into the BoB throughout the year with a peak in July-October. The riverine freshwater together with strong post-monsoon (October-November) coastal current generate complex and turbulent surface current pattern with a large number of eddies in the BoB. The wind forcing, coastal currents, and bathymetry make favorable conditions for the generation of eddies in the BoB. In the present study, a numerical ocean model Regional Ocean Modelling System (ROMS) used to simulate the mesoscale eddies in the BoB. The ROMS model uses sigma vertical coordinates which helps in taking account of the effects of coastal and bathymetrical structures on surface circulation and eddy generation. The model results are verified with the available observations. For the detection and tracking of eddies at the surface, both the geometrical and dynamical methods are used. The geometrical method is based on the identification of local minima and maxima of dynamic sea surface height. Whereas, the dynamical method utilizes current turbulences arising from strain or vorticity to identify eddies. Using model simulations, the cyclonic and anticyclonic eddies are identified in the BoB. The life span (time period) and the kinetic energy of individual eddies are calculated. The spatial and temporal distribution of eddies and their energetics in the BoB are discussed. Further, the propagation tracks of individual eddies are estimated.&lt;/p&gt;

scholarly journals Sensitivity study of wind forcing in a numerical model of mesoscale eddies in the lee of Hawaii islands

2010 ◽  
Vol 7 (2) ◽  
pp. 477-500 ◽  
Author(s):  
M. Kersalé ◽  
A. M. Doglioli ◽  
A. A. Petrenko
Keyword(s):  
Kinetic Energy ◽  
Ocean Circulation ◽  
Mesoscale Eddies ◽  
Sensitivity Study ◽  
Ocean Model ◽  
Wind Forcing ◽  
Trade Wind ◽  
Oceanic Circulation ◽  
Mesoscale Structures ◽  
And Behavior

Abstract. The oceanic circulation around the Hawaiian archipelago is characterized by a complex circulation and the presence of mesoscale eddies west of the islands. These eddies typically develop and persist for weeks to several months in the area during persistent trade wind conditions. In order to find the best setup of a regional ocean model and to better understand the role of the wind forcing in the eddy formation, we compare numerical results obtained using two different wind stress databases: COADS and QuikSCAT. A detailed comparative analysis of wind forcing, modeled kinetic energy and eddy generation is proposed. Moreover, numerical cyclonic eddies are compared with the ones observed during the cruises E-FLUX (Dickey et al., 2008). The main features of the ocean circulation in the area are well reproduced by our model forced by both COADS and QuickSCAT climatologies. Nevertheless, significant differences appear in the levels of kinetic energy and vorticity. The wind-forcing spatial resolution clearly affects the way in which the wind momentum feeds the mesoscale phenomena, and, the higher the resolution, the more realistic the ocean circulation. In particular, the simulation forced by QuikSCAT wind data reproduces well the observed energetic mesoscale structures and their hydrological characteristics and behavior.

Sign in / Sign up

Export Citation Format

Share Document