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    Analysis of Lagrangian Potential Vorticity Balance and Lateral Displacement of Water Parcels in Gulf Stream Meanders

    Source: Journal of Physical Oceanography:;1997:;Volume( 027 ):;issue: 002::page 325
    Author:
    Song, Tao
    ,
    Rossby, Tom
    DOI: 10.1175/1520-0485(1997)027<0325:AOLPVB>2.0.CO;2
    Publisher: American Meteorological Society
    Abstract: The balance of potential vorticity components following fluid parcel motion in Gulf Stream meanders was studied using RAFOS float data from the SYNOP Experiment. By introducing curvature dependent variations to the velocity and density fields, the authors relaxed the rigid field assumption used in earlier studies and examined closely 61 floats in the upper layers (13°?16°C) of the main thermocline. Float trajectories were segmented according to transition from crest to trough and trough to crest, and grouped by their positions relative to the current center. A total of 154 segments were collected to estimate the horizontal divergence and the mean lateral displacement of parcels under two distinct regimes: growing and decaying meanders. Both spatial and temporal changes in curvature affect the regions of divergence in a meandering stream. On the one hand, horizontal divergence increases with increasing curvature magnitude, while on the other hand, the divergence pattern itself changes going from growing to decaying meanders. The growing amplitude meanders (i.e., cases where the magnitude of curvature increases in time) are found to be associated with divergence (convergence) upstream, and convergence (divergence) downstream of crests on the anticyclonic (cyclonic) side. This pattern is reversed for decaying meanders. A parcel?s cross-stream motion is found to be consistent with the pattern established earlier: upwelling/onshore from trough to crest and downwelling/offshore from crest to trough. When referenced to the locus of the velocity maximum, which itself is curvature dependent, the mean cross-stream displacements of parcels on the cyclonic and anticyclonic sides appear to be opposite in direction relative to the current center and hence result in difluence (confluence) up- (down) stream of crests for growing amplitude meanders and vice versa for decaying ones. Cross-frontal fluid exchange is enhanced by changes in meander amplitude. The growth and decay of a meander are found to affect both the pathways and the intensity of fluid exchange. Comparisons of satellite IR imagery with RAFOS float trajectories suggest that the detraining of water associated with Gulf Stream meandering process occurs in both growing and decaying regimes.
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      Analysis of Lagrangian Potential Vorticity Balance and Lateral Displacement of Water Parcels in Gulf Stream Meanders

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    contributor authorSong, Tao
    contributor authorRossby, Tom
    date accessioned2017-06-09T14:52:27Z
    date available2017-06-09T14:52:27Z
    date copyright1997/02/01
    date issued1997
    identifier issn0022-3670
    identifier otherams-28661.pdf
    identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4165802
    description abstractThe balance of potential vorticity components following fluid parcel motion in Gulf Stream meanders was studied using RAFOS float data from the SYNOP Experiment. By introducing curvature dependent variations to the velocity and density fields, the authors relaxed the rigid field assumption used in earlier studies and examined closely 61 floats in the upper layers (13°?16°C) of the main thermocline. Float trajectories were segmented according to transition from crest to trough and trough to crest, and grouped by their positions relative to the current center. A total of 154 segments were collected to estimate the horizontal divergence and the mean lateral displacement of parcels under two distinct regimes: growing and decaying meanders. Both spatial and temporal changes in curvature affect the regions of divergence in a meandering stream. On the one hand, horizontal divergence increases with increasing curvature magnitude, while on the other hand, the divergence pattern itself changes going from growing to decaying meanders. The growing amplitude meanders (i.e., cases where the magnitude of curvature increases in time) are found to be associated with divergence (convergence) upstream, and convergence (divergence) downstream of crests on the anticyclonic (cyclonic) side. This pattern is reversed for decaying meanders. A parcel?s cross-stream motion is found to be consistent with the pattern established earlier: upwelling/onshore from trough to crest and downwelling/offshore from crest to trough. When referenced to the locus of the velocity maximum, which itself is curvature dependent, the mean cross-stream displacements of parcels on the cyclonic and anticyclonic sides appear to be opposite in direction relative to the current center and hence result in difluence (confluence) up- (down) stream of crests for growing amplitude meanders and vice versa for decaying ones. Cross-frontal fluid exchange is enhanced by changes in meander amplitude. The growth and decay of a meander are found to affect both the pathways and the intensity of fluid exchange. Comparisons of satellite IR imagery with RAFOS float trajectories suggest that the detraining of water associated with Gulf Stream meandering process occurs in both growing and decaying regimes.
    publisherAmerican Meteorological Society
    titleAnalysis of Lagrangian Potential Vorticity Balance and Lateral Displacement of Water Parcels in Gulf Stream Meanders
    typeJournal Paper
    journal volume27
    journal issue2
    journal titleJournal of Physical Oceanography
    identifier doi10.1175/1520-0485(1997)027<0325:AOLPVB>2.0.CO;2
    journal fristpage325
    journal lastpage339
    treeJournal of Physical Oceanography:;1997:;Volume( 027 ):;issue: 002
    contenttypeFulltext
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    DSpace software copyright © 2002-2015  DuraSpace
    نرم افزار کتابخانه دیجیتال "دی اسپیس" فارسی شده توسط یابش برای کتابخانه های ایرانی | تماس با یابش
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