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  • 1
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    The Halting Effect of Baroclinicity in Vortex Merging (2014)
    American Meteorological Society
    Details
    Publication Date: 2017-04-04
    Description: We study the quasi-geostrophic merging dynamics of axisymmetric baroclinic vortices to understand how baroclinicity affects merging rates and the development of the nonlinear cascade of enstrophy. The initial vortices are taken to simulate closely the horizontal' and vertical structure of Gulf Stream rings. A quasigeostrophic model is set with a horizontal resolution of 9 km and 6 vertical levels to resolve the mean stratification of the Gulf Stream region. The results show that the baroclinic merging is slower than the purely barotropic process, The merging is shown to occur in two phases: the tirst, which produces clove-shaped vortices and diffusive mixing of vorticity contours; and the second, which consists of the sliding of the remaining vorticity cores with a second diffusive mixing of the intemal vorticity field. Comparison among Nof, Cushman-Roisin, Polvani et al, and Dewar and Killworth merging events indicates a substantial agreement in the kinematics of the DYOCRSS. Parameter sensitivity experiments show that the decrease of the baroclinicity parameter of the system, Γ^2, [defined as Γ^2 = (D^2 fo^2)/ (No^2 H^2)], increases the speed of merging while its increase slows down the merging. However, the halting elfect of baroclinicity (large Γ^2 or small Rossby radii of deformation) reaches a saturation level where the merging becomes insensitive to larger F2 values. Furthermore, we show that a regime of small Γ^2 exists at which the merged baroclinic vortex is unstable (metastable) and breaks again into two new vortices, Thus, in the baroelinic case the range of Γ^2 detemines the stability of the merged vortex. We analyze these results by local energy and vorticity balances, showing that the horizontal divergence of pressure work term [∇ *(pv)] and the relative-vorticity advection term (v * ∇ (∇ ^2 φ) trigger the merging during the first phase. Due to this horizontal redistribution process, a net kinetic to gravitational energy conversion occurs via buoyancy work in the region external to the cores of the vortices. The second phase of merging is dominated by a direct baroclinic conversion of available gravitational energy into kinetic energy, which in tum triggers a horizontal energy redistribution producing the final fusion of the vortex centers. This energy and vorticity analysis supports the hypothesis that merging is an internal mixing process triggered by a horizontal redistribution of kinetic energy.
    Description: The work has been financed by a grant from the Progetto Finalizzato "Calcolo Parallelo"
    Description: Published
    Description: 1618/1637
    Description: 4A. Clima e Oceani
    Description: JCR Journal
    Description: restricted
    Keywords: Ocean modeling ; Vortex dynamics ; Baroclinicity ; Eddies ; 03. Hydrosphere::03.01. General::03.01.01. Analytical and numerical modeling
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Caribbean Current and eddies as observed by surface drifters (2006)
    Details
    Publication Date: 2017-01-04
    Description: Author Posting. © The Author, 2004. This is the author's version of the work. It is posted here by permission of Elsevier B. V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 52 (2005): 429-463, doi:10.1016/j.dsr2.2004.11.001.
    Description: Recent satellite-tracked surface drifter trajectories were analyzed to describe the mean currents and eddies in the Caribbean Sea. The structure of the Caribbean Current and its variability were determined from high-resolution ½ degree maps of the mean velocity and eddy kinetic energy. Looping drifter trajectories were used to identify discrete cyclones and anticyclones, and their characteristics were described and related to the structure of the mean flow. The translation rate of eddies in different areas was found to be similar to the mean velocity of the local background flow fields suggesting that the eddies were largely advected by the background flow. Ten energetic anticyclones translated westward at 13 cm/sec in the Venezuela and Colombia Basins. These anticyclones tended to lie in two bands, centered near 15ºN and 17ºN, coinciding with two jets of the Caribbean Current. The northern weaker jet contains water primarily from the North Atlantic, the southern stronger jet contains water from the tropical and South Atlantic. The anticyclones are thought to have formed in the eastern Caribbean from the anticyclonic vorticity derived from North Brazil Current rings. The ring vorticity enters the eastern Caribbean through island passages and is probably amplified by the anticyclonic shear on the northern side of the jets. Southwest of Cuba a cyclone-anticyclone pair was observed to slowly (~ 2 cm/sec) translate westward into the Yucatan Current. The cyclone was tracked for 10.5 months with four drifters, making it the longest-tracked of the Caribbean eddies.
    Description: Funding was provided by National Science Foundation grants OCE 97-29765 and OCE 01-36477.
    Keywords: Surface drifters ; Caribbean Current ; Caribbean eddies ; Eddies ; North Brazil Current rings ; Meridional overturning circulation ; Intra-Americas Seas ; Caribbean Sea ; Colombia Basin ; Venezuela Basin ; Yucatan Basin ; Antilles
    Repository Name: Woods Hole Open Access Server
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  • 3
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    Report of the First Meeting of the Climate Change Working Group 11-13 May 2011, Saly, Senegal. (2015)
    Project “Protection of the Canary Current Large Marine Ecosystem” | Dakar, Sénégal
    Details
    Publication Date: 2021-01-30
    Description: La première réunion du Comité de Pilotage du projet CCLME qui s'est tenue à Dakar, au Sénégal, le 4 novembre 2010 s’était accordée sur l’établissement de six groupes de travail techniques afin d’aider le processus de développement d'une Analyse Diagnostique Transfrontalière (ADT) et l'élaboration d'un Plan d'Action Stratégique (PAS) pour le CCLME. La réunion a également adopté leurs termes de référence. En outre, il a été convenu que le projet CCLME et les pays participants contribueraient au soutien et au renforcement des deux groupes de travail du COPACE sur l'évaluation des stocks des ressources démersales et pélagiques. La première réunion du Groupe de Travail sur les changements climatiques s'est tenue à Saly, au Sénégal, du 11 au 13 mai 2011. Les membres du groupe de travail ont été nommés par les pays membres et les institutions partenaires du CCLME. L'objectif global de la réunion était pour le groupe de travail de se mettre d'accord sur les grandes lignes d'un document sur les impacts du changement climatique et les stratégies d'adaptation et d'atténuation pour le CCLME, d’ identifier des activités de projets potentiels pour traiter des questions de changement climatique identifiées, d'attribuer des responsabilités au sein du groupe et de s'entendre sur un plan de travail pour la période 2011-2012 en tenant compte de la date prévue pour l’adoption de l’ADT (novembre 2012). Mme Isabelle Niang, coordonnatrice régionale du projet « Adaptation aux Changements Climatiques et Côtiers en Afrique de l’Ouest (ACCC), a été élue Présidente du groupe de travail. Les représentants des pays participants et des partenaires du CCLME ont présenté les principales questions liées au changement climatique, les principales activités entreprises pour y répondre, les questions qui restent à traiter et les stratégies proposées pour minimiser les effets négatifs du changement climatique sur les ressources et les écosystèmes marins en fonction de l'avis de leur pays ou de leur organisation. Deux groupes de travail ont été formés afin d'identifier les questions prioritaires et leurs causes et de recommander des domaines d'intervention relatifs aux impacts du changement climatique sur les ressources marines vivantes et sur la biodiversité, les habitats et la qualité de l'eau dans la zone du CCLME. Les groupes de travail ont défini un certain nombre de domaines prioritaires d'intervention nécessitant des fonds supplémentaires. Il s’agit des besoins de systèmes d'observation améliorés; d’une analyse et de la modélisation des données existantes; de la cartographie de la vulnérabilité des zones prioritaires pour le CCLME; de l’examen et du renforcement des Plans d'Action Nationaux pour l’Adaptation (PANA) en ce qui concerne la pêche ; de la restauration de la mangrove/des sources d'énergie alternatives. La réunion a également convenu d'un projet de plan pour le document sur les impacts du changement climatique et les stratégies d'adaptation et d'atténuation pour le CCLME ainsi que d'un plan de travail 2011-2012 pour le groupe de travail, avec des responsabilités définies.
    Description: The First CCLME Project Steering Committee Meeting that was held in Dakar, Senegal, the 4th of November 2010, agreed on the establishment of six CCLME technical working groups to assist the development process of a Transboundary Diagnostic Analysis (TDA) and the elaboration of a Strategic Action Plan (SAP) for the CCLME. The meeting also adopted their terms of references. In addition, it was agreed that the CCLME project and the participating countries would contribute to the maintenance and strengthening of two CECAF working groups on stock assessment of demersal and pelagic resources. The First Meeting of the Climate Change Working Group was held in Saly, Senegal from 11th to 13th of May 2011. The members of the working group had been nominated by the CCLME participating countries and partner institutions. The overall aim of the meeting was for the working group to agree on the outline of a document on climate change impacts and adaptation and mitigation strategies for the CCLME, to identify suitable potential project activities to address identified climate change issues, to assign responsibilities within the group and to agree on a work plan for the period 2011-2012 taking into consideration the expected date for the adoption of the TDA (November 2012). Ms Isabelle Niang, Regional coordinator of the project “Adaptation to Climate and Coastal Change in West Africa” (ACCC), was elected Chairperson of the working group. The CCLME participating countries and the partner representatives presented the main climate change issues, the main activities undertaken to address them, issues that remain to be addressed and suggested strategies to minimize negative effects of climate change on marine resources and ecosystems according to the view of their country or organization. Two groups were formed in order to identify priority issues and their causes and recommended domains of intervention regarding climate change impacts on marine living resources; and on biodiversity, habitat and water quality in the CCLME area. The working groups defined a number of priority areas of intervention in need of additional funds. These focused on the need for improved observation systems; further analysis and modelling of existing data; vulnerability mapping in priority areas for the CCLME; review and strengthening of National Adaptation Plans of Action (NAPAs) with regards to fisheries; and mangrove restoration / alternative energy sources. The meeting also agreed on a draft outline for the document on climate change impacts and adaptation and mitigation strategies for the CCLME as well as a 2011-2012 work plan for the working group with responsibilities assigned.
    Description: Fonds pour l’Environnement Mondial (FEM); co-financement despays participants et d’autres partenaires. Les partenaires actuels sont: l’Agence Française de Développement (AFD), la Commission Sous-Régionale des Pêches (CSRP), le projet EAF-Nansen, l’Administration Nationale des Océans et de l’Atmosphère (NOAA) des États-Unis d’Amérique, le Programme Régional de Conservation de la Zone Côtière et Marine en Afrique de l’Ouest (PRCM), l’Agence Suédoise de Coopération Internationale au Développement (SIDA) et WageningenInternational.
    Description: L’Organisation des Nations Unies pour l’alimentation et l’agriculture (FAO) et le Programme des Nations Unies pour l’Environnement (PNUE) sont les agences FEM pour la réalisation du projet CCLME. CCLME ou Canary Current Large Marine Ecosystem
    Description: Published
    Description: changement climatique
    Description: frontière
    Description: ressource pélagique
    Description: ressource demersale
    Description: mangrove
    Description: dégradation
    Description: sédimentation
    Description: eau
    Keywords: Changement climatique ; Climatic changes ; Boundary currents ; Pelagic fisheries ; Demersal fisheries ; Water resources ; Salinity ; Sedimentation ; Reefs (coral) ; Habitat degradation
    Repository Name: AquaDocs
    Type: Report , Not Known
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  • 4
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    Eddies and friction : removal of vorticity from the wind-driven gyre (2008)
    Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-25
    Description: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2003
    Description: Inertial terms dominate the single-gyre ocean model and prevent western-intensification when the viscosity is small. This occurs long before the oceanically-appropriate parameter range. It is demonstrated here that the circulation is controlled if a mechanism for ultimate removal of vorticity exists, even if it is active only in a narrow region near the boundary. Vorticity removal is modeled here as a viscosity enhanced very near the solid boundaries to roughly parameterize missing boundary physics like topographic interaction and three dimensional turbulence over the shelf. This boundary-enhanced viscosity allows western-intensified mean flows even when the inertial boundary width, is much wider than the frictional region because eddies flux vorticity from within the interior streamlines to the frictional region for removal. Using boundary-enhanced viscosity, western-intensified calculations are possible with lower interior viscosity than in previous studies. Interesting behaviors result: a boundary-layer balance novel to the model, calculations with promise for eddy parameterization, eddy-driven gyres rotating opposite the wind, and temporal complexity including basin resonances. I also demonstrate that multiple-gyre calculations have weaker mean circulation than single-gyres with the same viscosity and subtropical forcing. Despite traditional understanding, almost no inter-gyre flux occurs if no-slip boundary conditions are used. The inter-gyre eddy flux is in control only with exactly symmetric gyres and free slip boundaries. Even without the inter-gyre flux, the multiple-gyre circulation is weak because of sinuous instabilities on the jet which are not present in the single-gyre model. These modes efficiently flux vorticity to the boundary and reduce the circulation without an inter-gyre flux, postponing inertial domination to much smaller viscosities. Then sinuous modes in combination with boundary-enhanced viscosity can control the circulation.
    Keywords: Eddies ; Turbulent boundary layer ; Ocean-atmosphere interaction ; Mathematical models
    Repository Name: Woods Hole Open Access Server
    Type: Thesis
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  • 5
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    Monthly variability in upper ocean biogeochemistry due to mesoscale eddy activity in the Saragasso Sea (2009)
    Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-25
    Description: Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution May 2001
    Description: A comparison of monthly biogeochemical measurements made from 1993 to 1995, combined with hydrography and satellite altimetry, was used to observe the impacts of nine eddy events on primary productivity and particle flux in the Sargasso Sea. Measurements of primary production, thorium-234 flux, nitrate+nitrite, and photosynthetic pigments made at the US JGOFS Bermuda Atlantic Time-series Study (BATS) site were used. During the three years of this study, four out of six high thorium- 234 flux events over 1000 dpm/m2/d occurred during the passage of an eddy. Primary production nearly as high as the spring bloom maximum was observed in two modewater eddies (May 1993 and July 1995). The 1994 spring bloom at BATS was suppressed by the passage of an anticyclone. Distinct phytoplankton community shifts were observed in mode-water eddies, which had an increased percentage diatoms and dinoflagelletes, and in cyclones, which had an increased percentage cyanobacteria (excluding Prochlorococcus). The difference in the observations of mode-water eddies and cyclones may result from the age of the eddy, which was very important to the biological response. In general, eddies that were one to two months old elicited a large biological response; eddies that were three months old may show a biological response and were accompanied by high thorium flux measurements; eddies that were four months old or older did not show a biological response or high thorium flux. Our conceptual model depicting the importance of temporal changes during eddy upwelling and decay fit the observations well in all 7 upwelling eddies. Additional information is needed to determine the importance of deeper mixed layers and winter mixing to the magnitude of the eddy impacts. Also, sampling generally captured only the beginning, end, and lor edge of an eddy due to the monthly to semi-monthly frequency of the measurements made at BATS. Lagrangian studies, higher resolution time-series, and/or more spatial coverage is needed to provide additional information for improved C and N budgets in the Sargasso Sea and to complete our understanding of the temporal changes that occur in an eddy.
    Description: Funding for this work was provided by NASA and NSF through the JGOFS Synthesis and Modeling Program.
    Keywords: Eddies ; Biogeochemistry
    Repository Name: Woods Hole Open Access Server
    Type: Thesis
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  • 6
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    Eddy forcing of the mean circulation in the western North Atlantic (2010)
    Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-25
    Description: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution August 1984
    Description: This thesis addresses several aspects of the problem of determining the effect of the low-frequency eddy variability on the mean circulation of the Western North Atlantic. A framework for this study is first established by scale analysis of the eddy and mean terms in the mean momentum, vorticity, and heat balances in three regions of the Western North Atlantic -- the northern recirculation, the southern recirculation, and the mid-ocean. The data from the last decade of field experiments suggest somewhat different conclusions from the earlier analysis of Harrison (1980). In the momentum balance we confirm that the eddy terms are negligible compared to the lowest order mean geostrophic balance. The eddy term may be an 0(1) term in the vorticity balance only in the northern recirculation region where the mean flow is anisotropic. In the mean heat balance, if the mean temperature advection is scaled using the thermal wind relation, then the eddy heat flux is negligible in the mid-ocean, but it may be important in the recirculation areas. For all the balances the eddy terms are comparable to or an order of magnitude larger than the mean advective terms. We conclude from the scale analysis that the eddy field is most likely to be important in the Gulf Stream recirculation region. These balances are subsequently examined in more detail using data from the Local Dynamics Experiment (LDE). Several inconsistencies are first shown in McWilliams' (1983) model for the mean dynamical balances in the LDE. The sampling uncertainties do not allow us to draw conclusions about the long-term dynamical balances. However, it is shown that if we assume that the linear vorticity balance holds between the surface and the thermocline for a finite record, then the vertical velocity induced by the eddy heat flux divergence is non-zero. The local effect of the mesoscale eddy field on the mean potential vorticity distribution of the Gulf Stream recirculation region is determined from the quasigeostrophic eddy potential vorticity flux. This flux is calculated by finite difference of current and temperature time series from the Local Dynamics Experiment. This long-term array of moorings is the only experimental data from which the complete eddy flux can be calculated. The total eddy flux is dominated by the term due to the time variation in the thickness of isopycnal layers. This thickness flux is an order of magnitude larger than the relative vorticity flux. The total flux is statistically significant and directed 217° T to the southwest with a magnitude of 1.57 x 10 -5 cm/2s. The direction of the eddy flux with respect to the mean large scale potential vorticity gradient from hydrographic data indicates that eddies in this region tend to reduce the mean potential vorticity gradient. The results are qualitatively consistent with numerical model results and with other data from the Gulf Stream recirculation region. We find that the strength of the eddy transfer in the enstrophy cascade is comparable to the source terms in the mean enstrophy balance. The Austauch coefficient for potential vorticity mixing is estimated to be 0(107cm2/sec). An order of magnitude estimate of the enstrophy dissipation due only to the internal wave field shows that other processes must be important in enstrophy dissipation. The measured eddy potential vorticity fluxes are compared to the linear stability model of Gill, Green, and Simmons (1974). An earlier study (Hogg, 1984) has shown agreement between the empirical orthogonal modes of the data and the predicted wavenumbers, growth rates, and phase speeds of the most unstable waves. However, we show substantial disagreement in a comparison of the higher moments the eddy heat and potential vorticity fluxes. Because the critical layer of the model is located near the surface, the model predicts that most of the eddy potential vorticity and eddy heat flux should occur within about 300 meters of the surface. The data show much greater deep eddy heat flux than predicted by the model. It is suggested that the unstable modes in the ocean have a longer vertical scale because of the reduction in the buoyancy frequency near the surface. The evidence for in situ instability is also examined in the decay region of the Gulf Stream from an array of current and temperature recorders. Although there is vertical phase propagation in the empirical orthogonal modes for some of the variables at some of the moorings, there is not much evidence for a strong ongoing process of wave generation.
    Description: This research has been conducted under NSF contract numbers OCE 77-19403, ATM 79-21431, and OCE 82-00154.
    Keywords: Eddies ; Ocean currents
    Repository Name: Woods Hole Open Access Server
    Type: Thesis
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  • 7
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    Mesoscale eddy–internal wave coupling. Part II : energetics and results from PolyMode (2010)
    American Meteorological Society
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2010. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 40 (2010): 789-801, doi:10.1175/2009JPO4039.1.
    Description: The issue of internal wave–mesoscale eddy interactions is revisited. Previous observational work identified the mesoscale eddy field as a possible source of internal wave energy. Characterization of the coupling as a viscous process provides a smaller horizontal transfer coefficient than previously obtained, with vh 50 m2 s−1 in contrast to νh 200–400 m2 s−1, and a vertical transfer coefficient bounded away from zero, with νυ + (f2/N2)Kh 2.5 ± 0.3 × 10−3 m2 s−1 in contrast to νυ + (f2/N2)Kh = 0 ± 2 × 10−2 m2 s−1. Current meter data from the Local Dynamics Experiment of the PolyMode field program indicate mesoscale eddy–internal wave coupling through horizontal interactions (i) is a significant sink of eddy energy and (ii) plays an O(1) role in the energy budget of the internal wave field.
    Keywords: Eddies ; Internal waves ; Mesoscale processes
    Repository Name: Woods Hole Open Access Server
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  • 8
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    Mesoscale eddy-internal wave coupling. Part I : symmetry, wave capture, and results from the Mid-Ocean Dynamics Experiment (2010)
    American Meteorological Society
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 2556-2574, doi:10.1175/2008JPO3666.1.
    Description: Vertical profiles of horizontal velocity obtained during the Mid-Ocean Dynamics Experiment (MODE) provided the first published estimates of the high vertical wavenumber structure of horizontal velocity. The data were interpreted as being representative of the background internal wave field, and thus, despite some evidence of excess downward energy propagation associated with coherent near-inertial features that was interpreted in terms of atmospheric generation, these data provided the basis for a revision to the Garrett and Munk spectral model. These data are reinterpreted through the lens of 30 years of research. Rather than representing the background wave field, atmospheric generation, or even near-inertial wave trapping, the coherent high wavenumber features are characteristic of internal wave capture in a mesoscale strain field. Wave capture represents a generalization of critical layer events for flows lacking the spatial symmetry inherent in a parallel shear flow or isolated vortex.
    Description: Salary support for this analysis was provided by Woods Hole Oceanographic Institution bridge support funds.
    Keywords: Eddies ; Ocean dynamics ; Internal waves ; Ocean variability
    Repository Name: Woods Hole Open Access Server
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  • 9
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    Shelf circulation and cross-shelf transport out of a bay driven by eddies from an open-ocean current. Part I : interaction between a barotropic vortex and a steplike topography (2011)
    American Meteorological Society
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2011. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 41 (2011): 889–910, doi:10.1175/2010JPO4496.1.
    Description: This paper examines interaction between a barotropic point vortex and a steplike topography with a bay-shaped shelf. The interaction is governed by two mechanisms: propagation of topographic Rossby waves and advection by the forcing vortex. Topographic waves are supported by the potential vorticity (PV) jump across the topography and propagate along the step only in one direction, having higher PV on the right. Near one side boundary of the bay, which is in the wave propagation direction and has a narrow shelf, waves are blocked by the boundary, inducing strong out-of-bay transport in the form of detached crests. The wave–boundary interaction as well as out-of-bay transport is strengthened as the minimum shelf width is decreased. The two control mechanisms are related differently in anticyclone- and cyclone-induced interactions. In anticyclone-induced interactions, the PV front deformations are moved in opposite directions by the point vortex and topographic waves; a topographic cyclone forms out of the balance between the two opposing mechanisms and is advected by the forcing vortex into the deep ocean. In cyclone-induced interactions, the PV front deformations are moved in the same direction by the two mechanisms; a topographic cyclone forms out of the wave–boundary interaction but is confined to the coast. Therefore, anticyclonic vortices are more capable of driving water off the topography. The anticyclone-induced transport is enhanced for smaller vortex–step distance or smaller topography when the vortex advection is relatively strong compared to the wave propagation mechanism.
    Description: Y. Zhang acknowledges the support of theMIT-WHOI Joint Programin Physical Oceanography, NSF OCE-9901654 and OCE-0451086. J. Pedlosky acknowledges the support of NSF OCE- 9901654 and OCE-0451086.
    Keywords: Transport ; Eddies ; Barotropic flow ; Topographic effects ; Vortices ; Currents ; Potential vorticity ; Rossby waves
    Repository Name: Woods Hole Open Access Server
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  • 10
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    On the role of eddies and surface forcing in the heat transport and overturning circulation in marginal seas (2011)
    American Meteorological Society
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2011. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 24 (2011): 4844–4858, doi:10.1175/2011JCLI4130.1.
    Description: The factors that determine the heat transport and overturning circulation in marginal seas subject to wind forcing and heat loss to the atmosphere are explored using a combination of a high-resolution ocean circulation model and a simple conceptual model. The study is motivated by the exchange between the subpolar North Atlantic Ocean and the Nordic Seas, a region that is of central importance to the oceanic thermohaline circulation. It is shown that mesoscale eddies formed in the marginal sea play a major role in determining the mean meridional heat transport and meridional overturning circulation across the sill. The balance between the oceanic eddy heat flux and atmospheric cooling, as characterized by a nondimensional number, is shown to be the primary factor in determining the properties of the exchange. Results from a series of eddy-resolving primitive equation model calculations for the meridional heat transport, overturning circulation, density of convective waters, and density of exported waters compare well with predictions from the conceptual model over a wide range of parameter space. Scaling and model results indicate that wind effects are small and the mean exchange is primarily buoyancy forced. These results imply that one must accurately resolve or parameterize eddy fluxes in order to properly represent the mean exchange between the North Atlantic and the Nordic Seas, and thus between the Nordic Seas and the atmosphere, in climate models.
    Description: This study was supported by the National Science Foundation under Grants OCE-0726339 and OCE-0850416.
    Keywords: Eddies ; Forcing ; Meridional overturning circulation ; Transport ; North Atlantic Ocean ; Seas/gulfs/bays
    Repository Name: Woods Hole Open Access Server
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