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  • 11
    Online Resource
    Online Resource
    Journal of Marine Research/Yale ; 2014
    In:  Journal of Marine Research Vol. 72, No. 2 ( 2014-03-01), p. 73-94
    In: Journal of Marine Research, Journal of Marine Research/Yale, Vol. 72, No. 2 ( 2014-03-01), p. 73-94
    Type of Medium: Online Resource
    ISSN: 0022-2402 , 1543-9542
    Language: English
    Publisher: Journal of Marine Research/Yale
    Publication Date: 2014
    detail.hit.zdb_id: 410655-6
    detail.hit.zdb_id: 2066603-2
    SSG: 12
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  • 12
    Online Resource
    Online Resource
    American Meteorological Society ; 2008
    In:  Journal of Physical Oceanography Vol. 38, No. 12 ( 2008-12-01), p. 2704-2721
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 38, No. 12 ( 2008-12-01), p. 2704-2721
    Abstract: The issue of downwelling resulting from surface buoyancy loss in boundary currents is addressed using a high-resolution, nonhydrostatic numerical model. It is shown that the net downwelling is determined by the change in the mixed layer density along the boundary. For configurations in which the density on the boundary increases in the direction of Kelvin wave propagation, there is a net downwelling within the domain. For cases in which the density decreases in the direction of Kelvin wave propagation, cooling results in a net upwelling within the domain. Symmetric instability within the mixed layer drives an overturning cell in the interior, but it does not contribute to the net vertical motion. The net downwelling is determined by the geostrophic flow toward the boundary and is carried downward in a very narrow boundary layer of width E1/3, where E is the Ekman number. For the calculations here, this boundary layer is O(100 m) wide. A simple model of the mixed layer temperature that balances horizontal advection with surface cooling is used to predict the net downwelling and its dependence on external parameters. This model shows that the net sinking rate within the domain depends not only on the amount of heat loss at the surface but also on the Coriolis parameter, the mixed layer depth (or underlying stratification), and the horizontal velocity. These results indicate that if one is to correctly represent the buoyancy-forced downwelling in general circulation models, then it is crucial to accurately represent the velocity and mixed layer depth very close to the boundary. These results also imply that processes that lead to weak mixing within a few kilometers of the boundary, such as ice formation or freshwater runoff, can severely limit the downwelling forced by surface cooling, even if there is strong heat loss and convection farther offshore.
    Type of Medium: Online Resource
    ISSN: 1520-0485 , 0022-3670
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2008
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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  • 13
    Online Resource
    Online Resource
    American Meteorological Society ; 2015
    In:  Journal of Physical Oceanography Vol. 45, No. 11 ( 2015-11), p. 2820-2835
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 45, No. 11 ( 2015-11), p. 2820-2835
    Abstract: The response of a convective ocean basin to variations in atmospheric temperature is explored using numerical models and theory. The results indicate that the general behavior depends strongly on the frequency at which the atmosphere changes relative to the local response time to air–sea heat flux. For high-frequency forcing, the convective region in the basin interior is essentially one-dimensional and responds to the integrated local surface heat flux anomalies. For low-frequency forcing, eddy fluxes from the boundary current into the basin interior become important and act to suppress variability forced by the atmosphere. A theory is developed to quantify this time-dependent response and its influence on various oceanic quantities. The amplitude and phase of the temperature and salinity of the convective water mass, the meridional overturning circulation, the meridional heat flux, and the air–sea heat flux predicted by the theory compare well with that diagnosed from a series of numerical model calculations in both strongly eddying and weakly eddying regimes. Linearized analytic solutions provide direct estimates of each of these quantities and demonstrate their dependence on the nondimensional numbers that characterize the domain and atmospheric forcing. These results highlight the importance of mesoscale eddies in modulating the mean and time-dependent ocean response to atmospheric variability and provide a dynamical framework with which to connect ocean observations with changes in the atmosphere and surface heat flux.
    Type of Medium: Online Resource
    ISSN: 0022-3670 , 1520-0485
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2015
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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  • 14
    Online Resource
    Online Resource
    American Meteorological Society ; 2007
    In:  Journal of Climate Vol. 20, No. 15 ( 2007-08-01), p. 3785-3801
    In: Journal of Climate, American Meteorological Society, Vol. 20, No. 15 ( 2007-08-01), p. 3785-3801
    Abstract: The influences of strong gradients in sea surface temperature on near-surface cross-front winds are explored in a series of idealized numerical modeling experiments. The atmospheric model is the Naval Research Laboratory Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) model, which is fully coupled to the Regional Ocean Modeling System (ROMS) ocean model. A series of idealized, two-dimensional model calculations is carried out in which the wind blows from the warm-to-cold side or the cold-to-warm side of an initially prescribed ocean front. The evolution of the near-surface winds, boundary layer, and thermal structure is described, and the balances in the momentum equation are diagnosed. The changes in surface winds across the front are consistent with previous models and observations, showing a strong positive correlation with the sea surface temperature and boundary layer thickness. The coupling arises mainly as a result of changes in the flux Richardson number across the front, and the strength of the coupling coefficient grows quadratically with the strength of the cross-front geostrophic wind. The acceleration of the winds over warm water results primarily from the rapid change in turbulent mixing and the resulting unbalanced Coriolis force in the vicinity of the front. Much of the loss/gain of momentum perpendicular to the front in the upper and lower boundary layer results from acceleration/deceleration of the flow parallel to the front via the Coriolis term. This mechanism is different from the previously suggested processes of downward mixing of momentum and adjustment to the horizontal pressure gradient, and is active for flows off the equator with sufficiently strong winds. Although the main focus of this work is on the midlatitude, strong wind regime, calculations at low latitudes and with weak winds show that the pressure gradient and turbulent mixing terms dominate the cross-front momentum budget, consistent with previous work.
    Type of Medium: Online Resource
    ISSN: 1520-0442 , 0894-8755
    RVK:
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2007
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 15
    Online Resource
    Online Resource
    Elsevier BV ; 1999
    In:  Deep Sea Research Part II: Topical Studies in Oceanography Vol. 46, No. 1-2 ( 1999-1), p. 181-204
    In: Deep Sea Research Part II: Topical Studies in Oceanography, Elsevier BV, Vol. 46, No. 1-2 ( 1999-1), p. 181-204
    Type of Medium: Online Resource
    ISSN: 0967-0645
    Language: English
    Publisher: Elsevier BV
    Publication Date: 1999
    detail.hit.zdb_id: 1141627-0
    detail.hit.zdb_id: 1500312-7
    SSG: 14
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  • 16
    Online Resource
    Online Resource
    Elsevier BV ; 2019
    In:  Deep Sea Research Part II: Topical Studies in Oceanography Vol. 162 ( 2019-04), p. 79-92
    In: Deep Sea Research Part II: Topical Studies in Oceanography, Elsevier BV, Vol. 162 ( 2019-04), p. 79-92
    Type of Medium: Online Resource
    ISSN: 0967-0645
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2019
    detail.hit.zdb_id: 1141627-0
    detail.hit.zdb_id: 1500312-7
    SSG: 14
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  • 17
    Online Resource
    Online Resource
    American Meteorological Society ; 2013
    In:  Journal of Physical Oceanography Vol. 43, No. 5 ( 2013-05-01), p. 1028-1041
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 43, No. 5 ( 2013-05-01), p. 1028-1041
    Abstract: The circulation induced by the interaction of surface Ekman transport with an island is considered using both numerical models and linear theory. The basic response is similar to that found for the interaction of Ekman layers and an infinite boundary, namely downwelling (upwelling) in narrow boundary layers and deformation-scale baroclinic boundary layers with associated strong geostrophic flows. The presence of the island boundary, however, allows the pressure signal to propagate around the island so that the regions of upwelling and downwelling are dynamically connected. In the absence of stratification the island acts as an effective barrier to the Ekman transport. The presence of stratification supports baroclinic boundary currents that provide an advective pathway from one side of the island to the other. The resulting steady circulation is quite complex. Near the island, both geostrophic and ageostrophic velocity components are typically large. The density anomaly is maximum below the surface and, for positive wind stress, exhibits an anticyclonic phase rotation with depth (direction of Kelvin wave propagation) such that anomalously warm water can lie below regions of Ekman upwelling. The horizontal and vertical velocities exhibit similar phase changes with depth. The addition of a sloping bottom can act to shield the deep return flow from interacting with the island and providing mass transport into/out of the surface Ekman layer. In these cases, the required transport is provided by a pair of recirculation gyres that connect the narrow upwelling/downwelling boundary layers on the eastern and western sides of the island, thus directly connecting the Ekman transport across the island.
    Type of Medium: Online Resource
    ISSN: 0022-3670 , 1520-0485
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2013
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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  • 18
    Online Resource
    Online Resource
    American Meteorological Society ; 1990
    In:  Journal of Physical Oceanography Vol. 20, No. 7 ( 1990-07), p. 985-1016
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 20, No. 7 ( 1990-07), p. 985-1016
    Type of Medium: Online Resource
    ISSN: 0022-3670 , 1520-0485
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 1990
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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  • 19
    Online Resource
    Online Resource
    American Meteorological Society ; 2013
    In:  Journal of Physical Oceanography Vol. 43, No. 11 ( 2013-11-01), p. 2352-2371
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 43, No. 11 ( 2013-11-01), p. 2352-2371
    Abstract: An idealized eddy-resolving numerical model and an analytic three-layer model are used to develop ideas about what controls the circulation of Atlantic Water in the Arctic Ocean. The numerical model is forced with a surface heat flux, uniform winds, and a source of low-salinity water near the surface around the perimeter of an Arctic basin. Despite this idealized configuration, the model is able to reproduce many general aspects of the Arctic Ocean circulation and hydrography, including exchange through Fram Strait, circulation of Atlantic Water, a halocline, ice cover and transport, surface heat flux, and a Beaufort Gyre. The analytic model depends on a nondimensional number, and provides theoretical estimates of the halocline depth, stratification, freshwater content, and baroclinic shear in the boundary current. An empirical relationship between freshwater content and sea surface height allows for a prediction of the transport of Atlantic Water in the cyclonic boundary current. Parameters typical of the Arctic Ocean produce a cyclonic boundary current of Atlantic Water of O(1 − 2 Sv; where 1 Sv ≡ 106 m3 s−1) and a halocline depth of O(200 m), in reasonable agreement with observations. The theory compares well with a series of numerical model calculations in which mixing and environmental parameters are varied, thus lending credibility to the dynamics of the analytic model. In these models, lateral eddy fluxes from the boundary and vertical diffusion in the interior are important drivers of the halocline and the circulation of Atlantic Water in the Arctic Ocean.
    Type of Medium: Online Resource
    ISSN: 0022-3670 , 1520-0485
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2013
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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  • 20
    Online Resource
    Online Resource
    American Meteorological Society ; 2003
    In:  Journal of Physical Oceanography Vol. 33, No. 8 ( 2003-08-01), p. 1829-1845
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 33, No. 8 ( 2003-08-01), p. 1829-1845
    Abstract: It is demonstrated that recently observed cyclonic recirculation gyres in the Irminger and Labrador Seas may be forced by the strong cyclonic wind stress curl that develops each winter seaward of the east coast of Greenland. Idealized analytical and numerical models forced with such variable winds over a sloping bottom reproduce the essential aspects of the observed gyres (strength, location, and horizontal and vertical length scales). The communication between the forcing region in the Irminger Sea and the recirculation to the west is achieved by baroclinic topographic Rossby wave propagation along potential vorticity contours. The circulation is characterized as a time-dependent, stratified, topographic beta plume. For weak stratification, as found in the subpolar North Atlantic, the recirculation strength exhibits only weak seasonal variability, consistent with the observations, even though the forcing is active only during the winter. Baroclinic Rossby waves that develop when the wind forcing ceases in springtime interact with the bottom to provide a source of cyclonic vorticity that maintains the circulation until the wind strengthens again in the following winter.
    Type of Medium: Online Resource
    ISSN: 1520-0485 , 0022-3670
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2003
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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