scholarly journals Kinematic dynamo by large scale tsunami waves in open ocean

2013 ◽  
Vol 3 (3) ◽  
pp. 032003
Author(s):  
Benlong Wang ◽  
Hua Liu
Keyword(s):  
Large Scale ◽  
Open Ocean ◽  
Tsunami Waves ◽  
Kinematic Dynamo

scholarly journals Biases in Thorpe-Scale Estimates of Turbulence Dissipation. Part I: Assessments from Large-Scale Overturns in Oceanographic Data

2015 ◽  
Vol 45 (10) ◽  
pp. 2497-2521 ◽  
Author(s):  
Benjamin D. Mater ◽  
Subhas K. Venayagamoorthy ◽  
Louis St. Laurent ◽  
James N. Moum
Keyword(s):  
Large Scale ◽  
Companion Paper ◽  
Open Ocean ◽  
Luzon Strait ◽  
Length Scale ◽  
Ensemble Averaging ◽  
Tidal Period ◽  
Thorpe Scale ◽  
Order Of Magnitude ◽  
A Site

AbstractOceanic density overturns are commonly used to parameterize the dissipation rate of turbulent kinetic energy. This method assumes a linear scaling between the Thorpe length scale LT and the Ozmidov length scale LO. Historic evidence supporting LT ~ LO has been shown for relatively weak shear-driven turbulence of the thermocline; however, little support for the method exists in regions of turbulence driven by the convective collapse of topographically influenced overturns that are large by open-ocean standards. This study presents a direct comparison of LT and LO, using vertical profiles of temperature and microstructure shear collected in the Luzon Strait—a site characterized by topographically influenced overturns up to O(100) m in scale. The comparison is also done for open-ocean sites in the Brazil basin and North Atlantic where overturns are generally smaller and due to different processes. A key result is that LT/LO increases with overturn size in a fashion similar to that observed in numerical studies of Kelvin–Helmholtz (K–H) instabilities for all sites but is most clear in data from the Luzon Strait. Resultant bias in parameterized dissipation is mitigated by ensemble averaging; however, a positive bias appears when instantaneous observations are depth and time integrated. For a series of profiles taken during a spring tidal period in the Luzon Strait, the integrated value is nearly an order of magnitude larger than that based on the microstructure observations. Physical arguments supporting LT ~ LO are revisited, and conceptual regimes explaining the relationship between LT/LO and a nondimensional overturn size are proposed. In a companion paper, Scotti obtains similar conclusions from energetics arguments and simulations.

scholarly journals Transport by deep convection in basin-scale geostrophic circulation: turbulence-resolving simulations

2019 ◽  
Vol 865 ◽  
pp. 681-719
Author(s):  
Catherine A. Vreugdenhil ◽  
Bishakhdatta Gayen ◽  
Ross W. Griffiths
Keyword(s):  
Boundary Layer ◽  
Thermal Boundary Layer ◽  
Large Scale ◽  
Deep Convection ◽  
Ocean Basin ◽  
Open Ocean ◽  
Small Scale ◽  
Large Scale Circulation ◽  
Buoyancy Forcing ◽  
Basin Scale

Direct numerical simulations are used to investigate the nature of fully resolved small-scale convection and its role in large-scale circulation in a rotating $f$-plane rectangular basin with imposed surface temperature difference. The large-scale circulation has a horizontal geostrophic component and a deep vertical overturning. This paper focuses on convective circulation with no wind stress, and buoyancy forcing sufficiently strong to ensure turbulent convection within the thermal boundary layer (horizontal Rayleigh numbers $Ra\approx 10^{12}{-}10^{13}$). The dynamics are found to depend on the value of a convective Rossby number, $Ro_{\unicode[STIX]{x0394}T}$, which represents the strength of buoyancy forcing relative to Coriolis forces. Vertical convection shifts from a mean endwall plume under weak rotation ($Ro_{\unicode[STIX]{x0394}T}>10^{-1}$) to ‘open ocean’ chimney convection plus mean vertical plumes at the side boundaries under strong rotation ($Ro_{\unicode[STIX]{x0394}T}<10^{-1}$). The overall heat throughput, horizontal gyre transport and zonally integrated overturning transport are then consistent with scaling predictions for flow constrained by thermal wind balance in the thermal boundary layer coupled to vertical advection–diffusion balance in the boundary layer. For small Rossby numbers relevant to circulation in an ocean basin, vertical heat transport from the surface layer into the deep interior occurs mostly in ‘open ocean’ chimney convection while most vertical mass transport is against the side boundaries. Both heat throughput and the mean circulation (in geostrophic gyres, boundary currents and overturning) are reduced by geostrophic constraints.

Gulf stream cold core rings: large-scale interaction sites for open ocean plankton communities

1976 ◽  
Vol 23 (8) ◽  
pp. 695-710 ◽  
Author(s):  
Peter H. Wiebe ◽  
Edward M. Hulburt ◽  
Edward J. Carpenter ◽  
Andrew E. Jahn ◽  
George P. Knapp ◽  
...  
Keyword(s):  
Gulf Stream ◽  
Large Scale ◽  
Open Ocean ◽  
Scale Interaction ◽  
Interaction Sites ◽  
Cold Core ◽  
Plankton Communities

CFD simulations of tsunamis from large scale propagation up to local coastal impacts

2020 ◽  
Author(s):  
Richard Marcer ◽  
Camille Journeau ◽  
Kévin Pons
Keyword(s):  
Adaptive Mesh Refinement ◽  
Large Scale ◽  
Adaptive Mesh ◽  
Navier Stokes ◽  
Water Volume ◽  
Tsunami Propagation ◽  
Tsunami Modelling ◽  
Tsunami Waves ◽  
In Situ Data ◽  
Run Up

&lt;p&gt;This work has been performed within the framework of the TANDEM project (Tsunamis in northern AtlaNtic: Definition of Effects by Modelling) which is dedicated to the appraisal of coastal effects due to tsunami waves on the French coastlines. One of the identified objectives of TANDEM consisted in designing, adapting and validating numerical codes for tsunami hazard assessment, addressing the various stages of a tsunami event: generation, propagation, run-up and coastal inundation.&lt;/p&gt;&lt;p&gt;PRINCIPIA has been working on the development and qualification of two in-house CFD software&amp;#8217;s: a 2D Saint-Venant model (often called NLSW for Non-Linear Shallow Water) using an Adaptive Mesh Refinement (AMR) for simulation of large scale tsunami propagation from the source up to coastal scale, and a 3D Navier-Stokes model dedicated to tsunami coastal impact modelling.&lt;/p&gt;&lt;p&gt;An overview of the results obtained with both codes aiming at being applicable to tsunami modelling, is presented. The validation process has been done on several academic test cases having experimental data for comparisons, as the breaking of a solitary wave on a reef, the generation of a long wave induced by a vertical bloc (massive cliffs, ice bodies) falling down an underlying water volume, the tsunami generation due to a submarine landslide and the tsunami impact on a coastal city.&lt;/p&gt;&lt;p&gt;A real case simulation is concerned as well, the devastating 2011 Tohoku event which is compared with in-situ data.&lt;/p&gt;&lt;p&gt;The work was supported by the Tandem project in the frame of French PIA grant ANR-11-RSNR-00023.&lt;/p&gt;

Zero-fuel open ocean-going tugs, and applications for the large scale collection of ocean plastics

2019 ◽  
Author(s):  
Danny Golden ◽  
Joss Fitzimons ◽  
Tom Doyle ◽  
Darren Hayes
Keyword(s):  
Large Scale ◽  
Open Ocean

Topographic Influences on the Wind-driven Exchange Between Marginal Seas and the Open Ocean

2021 ◽  
Author(s):  
Haihong Guo ◽  
Michael A. Spall
Keyword(s):  
Large Scale ◽  
Low Frequency ◽  
Open Ocean ◽  
Ekman Transport ◽  
Analytical Models ◽  
Island Rule ◽  
Marginal Seas ◽  
Zonal Jets ◽  
Marginal Sea ◽  
The Western Pacific

AbstractThe wind-driven exchange through complex ridges and islands between marginal seas and the open ocean is studied using both numerical and analytical models. The models are forced by a steady, spatially uniform northward wind stress intended to represent the large-scale, low-frequency wind patterns typical of the seasonal monsoons in the western Pacific Ocean. There is an eastward surface Ekman transport out of the marginal sea and westward geostrophic inflows into the marginal sea. The interaction between the Ekman transport and an island chain produces strong baroclinic flows along the island boundaries with a vertical depth that scales with the ratio of the inertial boundary layer thickness to the baroclinic deformation radius. The throughflows in the gaps are characterized by maximum transport in the center gap and decreasing transports towards the southern and northern tips of the island chain. An extended island rule theory demonstrates that throughflows are determined by the collective balance between viscosity on the meridional boundaries and the eastern side boundary of the islands. The outflowing transport is balanced primarily by a shallow current that enters the marginal sea along its equatorward boundary. The islands can block some direct exchange and result in a wind-driven overturning cell within the marginal sea, but this is compensated for by eastward zonal jets around the southern and northern tips of the island chain. Topography in the form of a deep slope, a ridge, or shallow shelves around the islands alters the current pathways but ultimately is unable to limit the total wind-driven exchange between the marginal sea and the open ocean.

LARGE-SCALE DIVERSITY PATTERNS OF CEPHALOPODS IN THE ATLANTIC OPEN OCEAN AND DEEP SEA

Ecology ◽  
2008 ◽  
Vol 89 (12) ◽  
pp. 3449-3461 ◽  
Author(s):  
Rui Rosa ◽  
Heidi M. Dierssen ◽  
Liliana Gonzalez ◽  
Brad A. Seibel
Keyword(s):  
Deep Sea ◽  
Large Scale ◽  
Open Ocean ◽  
Diversity Patterns

scholarly journals CHALLENGES OF BOUNDARY CONDITIONS IN OPEN OCEAN MODELS

2020 ◽  
pp. 52
Author(s):  
Judith Herold ◽  
Eric Lemont ◽  
Stuart Bettington ◽  
Edward Couriel
Keyword(s):  
Environmental Impact ◽  
Boundary Conditions ◽  
Large Scale ◽  
Numerical Models ◽  
Open Ocean ◽  
Small Scale ◽  
Ocean Models ◽  
Support Engineering ◽  
Ocean Boundary ◽  
Professional Judgement

The development and calibration of coastal numerical models to support engineering design and environmental impact studies is a challenging process and one that requires professional judgement and continual assessment of all aspects of the model makeup. Fundamental to the integrity of the model are appropriate boundary conditions and quality observational data for calibration. Open ocean boundary conditions are typically the most complex and important aspect of a model build. They represent the influence of dynamics occurring beyond the model extent, bridging large-scale dynamics to the small-scale processes in the model. This study discusses the challenges of open ocean boundaries and how we utilised data to achieve an effective model.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/evL7f_17wZg

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