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  • 11
    Online Resource
    Online Resource
    Causes of Interannual–Decadal Variability in the Meridional Overturning Circulation of the Midlatitude North Atlantic Ocean
    American Meteorological Society ; 2008
    In:  Journal of Climate Vol. 21, No. 24 ( 2008-12-15), p. 6599-6615
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 21, No. 24 ( 2008-12-15), p. 6599-6615
    Abstract: The causes and characteristics of interannual–decadal variability of the meridional overturning circulation (MOC) in the North Atlantic are investigated with a suite of basin-scale ocean models [the Family of Linked Atlantic Model Experiments (FLAME)] and global ocean–ice models (ORCA), varying in resolution from medium to eddy resolving (½°–1/12°), using various forcing configurations built on bulk formulations invoking atmospheric reanalysis products. Comparison of the model hindcasts indicates similar MOC variability characteristics on time scales up to a decade; both model architectures also simulate an upward trend in MOC strength between the early 1970s and mid-1990s. The causes of the MOC changes are examined by perturbation experiments aimed selectively at the response to individual forcing components. The solutions emphasize an inherently linear character of the midlatitude MOC variability by demonstrating that the anomalies of a (non–eddy resolving) hindcast simulation can be understood as a superposition of decadal and longer-term signals originating from thermohaline forcing variability, and a higher-frequency wind-driven variability. The thermohaline MOC signal is linked to the variability in subarctic deep-water formation, and rapidly progressing to the tropical Atlantic. However, throughout the subtropical and midlatitude North Atlantic, this signal is effectively masked by stronger MOC variability related to wind forcing and, especially north of 30°–35°N, by internally induced (eddy) fluctuations.
    Type of Medium: Online Resource
    ISSN: 1520-0442 , 0894-8755
    URL: Article
    DOI: 10.1175/2008JCLI2404.1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2008
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 12
    Online Resource
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    Water Mass Analysis of Effect of Climate Change on Air–Sea CO 2 Fluxes: The Southern Ocean
    American Meteorological Society ; 2012
    In:  Journal of Climate Vol. 25, No. 11 ( 2012-06), p. 3894-3908
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 25, No. 11 ( 2012-06), p. 3894-3908
    Abstract: Impacts of climate change on air–sea CO 2 exchange are strongly region dependent, particularly in the Southern Ocean. Yet, in the Southern Ocean the role of water masses in the uptake of anthropogenic carbon is still debated. Here, a methodology is applied that tracks the carbon flux of each Southern Ocean water mass in response to climate change. A global marine biogeochemical model was coupled to a climate model, making 140-yr Coupled Model Intercomparison Project phase 5 (CMIP5)-type simulations, where atmospheric CO 2 increased by 1% yr −1 to 4 times the preindustrial concentration (4 × CO 2 ). Impacts of atmospheric CO 2 (carbon-induced sensitivity) and climate change (climate-induced sensitivity) on the water mass carbon fluxes have been isolated performing two sensitivity simulations. In the first simulation, the atmospheric CO 2 influences solely the marine carbon cycle, while in the second simulation, it influences both the marine carbon cycle and earth’s climate. At 4 × CO 2 , the cumulative carbon uptake by the Southern Ocean reaches 278 PgC, 53% of which is taken up by modal and intermediate water masses. The carbon-induced and climate-induced sensitivities vary significantly between the water masses. The carbon-induced sensitivities enhance the carbon uptake of the water masses, particularly for the denser classes. But, enhancement strongly depends on the water mass structure. The climate-induced sensitivities either strengthen or weaken the carbon uptake and are influenced by local processes through changes in CO 2 solubility and stratification, and by large-scale changes in outcrop surface (OS) areas. Changes in OS areas account for 45% of the climate-induced reduction in the Southern Ocean carbon uptake and are a key factor in understanding the future carbon uptake of the Southern Ocean.
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/JCLI-D-11-00291.1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2012
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 13
    Online Resource
    Online Resource
    The March 1997 Westerly Wind Event and the Onset of the 1997/98 El Niño: Understanding the Role of the Atmospheric Response
    American Meteorological Society ; 2003
    In:  Journal of Climate Vol. 16, No. 20 ( 2003-10), p. 3330-3343
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 16, No. 20 ( 2003-10), p. 3330-3343
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/1520-0442(2003)016〈3330:TMWWEA〉2.0.CO;2
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2003
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 14
    Online Resource
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    Defining a Simplified Yet “Realistic” Equation of State for Seawater
    American Meteorological Society ; 2015
    In:  Journal of Physical Oceanography Vol. 45, No. 10 ( 2015-10), p. 2564-2579
    Details
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 45, No. 10 ( 2015-10), p. 2564-2579
    Abstract: There is a growing realization that the nonlinear nature of the equation of state has a deep impact on the global ocean circulation; however, the understanding of the global effects of these nonlinearities remains elusive. This is partly because of the complicated formulation of the seawater equation of state making it difficult to handle in theoretical studies. In this paper, a hierarchy of polynomial equations of state of increasing complexity, optimal in a least squares sense, is presented. These different simplified equations of state are then used to simulate the ocean circulation in a global 2°-resolution configuration. Comparisons between simulated ocean circulations confirm that nonlinear effects are of major importance, in particular influencing the circulation through determination of the static stability below the mixed layer, thus controlling rates of exchange between the atmosphere and the ocean interior. It is found that a simple polynomial equation of state, with a quadratic term in temperature (for cabbeling), a temperature–pressure product term (for thermobaricity), and a linear term in salinity, that is, only four tuning parameters, is enough to simulate a reasonably realistic global circulation. The best simulation is obtained when the simplified equation of state is forced to have an accurate thermal expansion coefficient near the freezing point, highlighting the importance of polar regions for the global stratification. It is argued that this simplified equation of state will be of great value for theoretical studies and pedagogical purposes.
    Type of Medium: Online Resource
    ISSN: 0022-3670 , 1520-0485
    URL: Article
    DOI: 10.1175/JPO-D-15-0080.1
    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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  • 15
    Online Resource
    Online Resource
    A Linear Decomposition of the Southern Ocean Thermohaline Structure
    American Meteorological Society ; 2017
    In:  Journal of Physical Oceanography Vol. 47, No. 1 ( 2017-01), p. 29-47
    Details
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 47, No. 1 ( 2017-01), p. 29-47
    Abstract: The thermohaline structure of the Southern Ocean is deeply influenced by the presence of the Antarctic Circumpolar Current (ACC), where water masses of the World Ocean are advected, transformed, and redistributed to the other basins. It remains a challenge to describe and visualize the complex 3D pattern of this circulation and its associated tracer distribution. Here, a simple framework is presented to analyze the Southern Ocean thermohaline structure. A functional principal component analysis (PCA) is applied to temperature θ and salinity S profiles to determine the main spatial patterns of their variations. Using the Southern Ocean State Estimate (SOSE), this study determines the vertical modes describing the Southern Ocean thermohaline structure between 5 and 2000 m. The first two modes explain 92% of the combined θ – S variance, thus providing a surprisingly good approximation of the thermohaline properties in the Southern Ocean. The first mode (72% of total variance) accurately describes the north–south property gradients. The second mode (20%) mostly describes salinity at 500 m in the region of Antarctic Intermediate Water formation. These two modes present circumpolar patterns that can be closely related with standard frontal definitions. By projecting any given hydrographic profile onto the SOSE-based modes, it is possible to determine its position relative to the fronts. The projection is successfully applied on the hydrographic profiles of the WOCE SR3 section. The Southern Ocean thermohaline decomposition provides an objective way to define water mass boundaries and their spatial variability and has useful application for comparing model output with observations.
    Type of Medium: Online Resource
    ISSN: 0022-3670 , 1520-0485
    URL: Article
    URL: Article
    DOI: 10.1175/JPO-D-16-0083.1
    DOI: 10.1175/JPO-D-16-0083.s1
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2017
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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  • 16
    Online Resource
    Online Resource
    The Impact of Satellite Winds and Latent Heat Fluxes in a Numerical Simulation of the Tropical Pacific Ocean
    American Meteorological Society ; 2006
    In:  Journal of Climate Vol. 19, No. 22 ( 2006-11-15), p. 5889-5902
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 19, No. 22 ( 2006-11-15), p. 5889-5902
    Abstract: Several oceanic operational programs use remotely sensed fluxes to complement atmospheric operational analyses from major national weather prediction centers. The main goal of this study is to evaluate the ability of the ocean model (ORCA) to correctly simulate the dynamic of the tropical Pacific Ocean in 1996–98 when forced by the satellite turbulent fluxes (wind stress and latent heat fluxes). The results are compared with the oceanic response resulting from forcing the model with the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis. Three sensitivity simulations forced with satellite and atmospheric analysis fields are performed. The control experiment is forced with the ECMWF fluxes. The solutions of these simulations are compared with data from the Tropical Atmosphere–Ocean (TAO) buoys and from sea surface temperatures analysis by Reynolds and Smith in the equatorial Pacific Ocean. The analysis results indicate that the model reproduces well the major spatial and temporal oceanic structures including the main characteristics of the 1997–98 El Niño. More specifically, the comparisons with buoys indicate that the experiment forced by the winds and the satellite latent heat fluxes is closer to the observations. They provide weak rms difference and strong correlations along the whole 500-m depth column. Furthermore, the correlations with the SST analysis vary between 75% and 95% compared to 65% and 77% for the experiment forced by ECMWF fluxes. The currents in the first 350 m also show a strong sensitivity to satellite turbulent fluxes.
    Type of Medium: Online Resource
    ISSN: 1520-0442 , 0894-8755
    URL: Article
    DOI: 10.1175/JCLI3939.1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2006
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 17
    Online Resource
    Online Resource
    The roles of surface heat flux and ocean heat transport convergence in determining Atlantic Ocean temperature variability
    Springer Science and Business Media LLC ; 2010
    In:  Ocean Dynamics Vol. 60, No. 4 ( 2010-8), p. 771-790
    Details
    In: Ocean Dynamics, Springer Science and Business Media LLC, Vol. 60, No. 4 ( 2010-8), p. 771-790
    Type of Medium: Online Resource
    ISSN: 1616-7341 , 1616-7228
    URL: Article
    DOI: 10.1007/s10236-010-0292-4
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2010
    detail.hit.zdb_id: 2063267-8
    detail.hit.zdb_id: 201122-0
    SSG: 14
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  • 18
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    Internal and forced variability along a section between Greenland and Portugal in the CLIPPER Atlantic model
    Springer Science and Business Media LLC ; 2006
    In:  Ocean Dynamics Vol. 56, No. 5-6 ( 2006-12-3), p. 568-580
    Details
    In: Ocean Dynamics, Springer Science and Business Media LLC, Vol. 56, No. 5-6 ( 2006-12-3), p. 568-580
    Type of Medium: Online Resource
    ISSN: 1616-7341 , 1616-7228
    URL: Article
    DOI: 10.1007/s10236-006-0069-y
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2006
    detail.hit.zdb_id: 2063267-8
    detail.hit.zdb_id: 201122-0
    SSG: 14
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  • 19
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    Online Resource
    An Exchange Window for the Injection of Antarctic Intermediate Water into the South Pacific
    American Meteorological Society ; 2007
    In:  Journal of Physical Oceanography Vol. 37, No. 1 ( 2007-01-01), p. 31-49
    Details
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 37, No. 1 ( 2007-01-01), p. 31-49
    Abstract: Antarctic Intermediate Water (AAIW) occupies the intermediate horizon of most of the world oceans. Formed in the Southern Ocean, it is characterized by a relative salinity minimum. With a new, denser in situ National Oceanographic Data Center dataset, the authors have reanalyzed the export characteristics of AAIW from the Southern Ocean into the South Pacific Ocean. These new data show that part of the AAIW is exported from the subpolar frontal region by the large-scale circulation through an exchange window of 10° width situated east of 90°W in the southeast corner of the Pacific basin. This suggests the origin of this water to be in the Antarctic Circumpolar Current. A set of numerical modeling experiments has been used to reproduce these observed features and to demonstrate that the dynamics of the exchange window is controlled by the basin-scale meridional pressure gradient. The exchange of AAIW between the Southern and Pacific Oceans must therefore be understood in the context of the large basin-scale dynamical balance rather than simply local effects.
    Type of Medium: Online Resource
    ISSN: 1520-0485 , 0022-3670
    URL: Article
    DOI: 10.1175/JPO2985.1
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2007
    detail.hit.zdb_id: 2042184-9
    detail.hit.zdb_id: 184162-2
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  • 20
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    Online Resource
    The Role of Southern Ocean Surface Forcings and Mixing in the Global Conveyor
    American Meteorological Society ; 2008
    In:  Journal of Physical Oceanography Vol. 38, No. 7 ( 2008-07-01), p. 1377-1400
    Details
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 38, No. 7 ( 2008-07-01), p. 1377-1400
    Abstract: Despite the renewed interest in the Southern Ocean, there are yet many unknowns because of the scarcity of measurements and the complexity of the thermohaline circulation. Hence the authors present here the analysis of the thermohaline circulation of the Southern Ocean of a steady-state simulation of a coupled ice–ocean model. The study aims to clarify the roles of surface fluxes and internal mixing, with focus on the mechanisms of the upper branch of the overturning. A quantitative dynamical analysis of the water-mass transformation has been performed using a new method. Surface fluxes, including the effect of the penetrative solar radiation, produce almost 40 Sv (1 Sv ≡ 106 m3 s−1) of Subantarctic Mode Water while about 5 Sv of the densest water masses (γ & gt; 28.2) are formed by brine rejection on the shelves of Antarctica and in the Weddell Sea. Mixing transforms one-half of the Subantarctic Mode Water into intermediate water and Upper Circumpolar Deep Water while bottom water is produced by Lower Circumpolar Deep Water and North Atlantic Deep Water mixing with shelf water. The upwelling of part of the North Atlantic Deep Water inflow is due to internal processes, mainly downward propagation of the surface freshwater excess via vertical mixing at the base of the mixed layer. A complementary Lagrangian analysis of the thermohaline circulation will be presented in a companion paper.
    Type of Medium: Online Resource
    ISSN: 1520-0485 , 0022-3670
    URL: Article
    DOI: 10.1175/2008JPO3519.1
    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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