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  • Ocean currents  (83)
  • Eddies  (74)
  • Atmosphere-ocean interaction  (51)
  • Internal waves  (50)
  • Mesoscale processes
  • American Meteorological Society  (155)
  • Woods Hole Oceanographic Institution  (100)
  • Instituto Oceanográfico de la Armada, Guayaquil, Ecuador  (4)
  • 1
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    American Meteorological Society
    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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    Instituto Oceanográfico de la Armada, Guayaquil, Ecuador
    Publication Date: 2021-05-19
    Description: Se presenta un estudio de las características de las aguas ecuatorianas, mediante el análisis químico de las muestras obtenidas durante los cruceros I y II realizados a bordo del BAE ORION en los meses de Agosto y Diiciembre de 1988. Se realiza las caracterización de los diferentes ambientes hasta los 100 m de profundidad, estableciéndose el comportamiento de los parámetros hidroquímicos, tanto en su distribución horizontal geográfica, como vertical en la columna de agua y su relación con el frente Ecuatorial. Se establece, en forma general, la influencia de la presencia de la Corriente de Humboldt, en la concentración y distribución de los parámetros en el CO-I-88; y el debilitamiento de la misma en el CO-II-88. Evideciándose por lo tanto, aguas más salinas, mayor oxigenadas y de más alta concentración de nutrientes en el CO-I-88 que en el CO-II-88. De la distribución horizontal de los parámetros hidroquímicos (0-20 m) durante los dos cruceros de 1988 permitió establecer la presencia de las aguas Tropicales Superficiales en la zona norte del frente, las cuales muestran menores concentraciones de fosfato, nitrito y nitrato en comparación con las aguas de corriente de Humboldt en el sur donde se registraron las más altas concentraciones. Con respecto a la capa de 50 - 100 m se observó la presencia de Aguas ecuatoriales Subsuperficiales las mismas que presentan bajo contenido de oxígeno, y altas concentraciones de nutrientes.
    Description: Incluye ref.bibl., grafs.
    Description: Published
    Keywords: Ocean currents ; Chemical oceanography ; Sea water ; Chemical oceanography ; Sea water ; Ocean currents
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 3
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    Instituto Oceanográfico de la Armada, Guayaquil, Ecuador
    Publication Date: 2021-05-19
    Description: De la información obtenida del crucero CO-1-88, llevado a cabo desde el 8 al 30 de agosto de 1988, se efectuó un análisis de ondas internas en el mar ecuatoriano, para lo cual se realizaron mediciones desde la superficie hasta los 500 metros durante observaciones continuas de 24 horas denominadas estaciones fijas, con un intervalo de 3 a 4 horas aproximadamente entre cada uno de los lances. Basándose en los registros de temperatura del agua de mar y relacionando este parámetro con las fluctuaciones de salinidad, densidad y velocidad del sonido se establece, en el Pacífico Ecuatorial oriental, la existencia de ondas internas. Su presencia fue mayormente observada en la zona de la termoclina, relacionada ésta a movimientos ascendentes y descendentes. Además, se pudo notar que este patrón de comportamiento de la temperatura incidía de una forma directa en el perfil de distribución de la salinidad como de densidad. Se encontró también una amplitud de onda de 40 metros aproximadamente, siendo igual coincidentemente para las tres estaciones fijas. La temperatura y velocidad del sonido tienen similitud en la distribución de sus perfiles y secciones sobre toda la columna de agua.
    Description: Incluye ref.bibl., grafs.
    Description: Published
    Keywords: Equatorial waves ; Internal waves ; Wave measurement
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 4
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    Instituto Oceanográfico de la Armada, Guayaquil, Ecuador
    Publication Date: 2021-05-19
    Description: Las ondas internas son movimientos ondulatorios en fluidos de estratificación estable, en los cuales la máxima amplitud del movimiento vertical tiene lugar en la zona por debajo de la interfase, la cual se encuentra entre las superficies del fluido. La principal fuerza de recuperación es la gravedad. Se cree que las ondas internas se generan en el mar por variaciones de la presión atmosférica y por influencia de ondas superficiales de baja frecuencia en aguas de profundidad variable. Las ondas internas pueden presentarse entre capas de diferentes densidades en el océano, porque la diferencia de densidades conlleva a una presión gravitacional o hidrostática que será una fuerza restuaradora si el fluido se desplaza verticalmente.
    Description: Internal waves are ondulatory movements in fluids of stable stratification in which the maximum amplitude of the vertical displacement take place below the boundary zone. The boundary zone is found between the layers of the fluid. The principal restoring force of the internal waves is the gravity. It is believed that internal waves in the sea are produced by the variation of the atmospheric pressure and by the influence of low frequency surface waves in waters of variable depth. Internal waves could be generated between layers of different densities and as a result of this variation a gravitational or hidrostatic pressure take place which will be a restoring force if the fluid is vertically displaced.
    Description: Incluye ref.bibl., ilus.
    Description: Published
    Keywords: Internal waves ; Surface wave-internal wave interactions
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 5
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    Instituto Oceanográfico de la Armada, Guayaquil, Ecuador
    Publication Date: 2021-05-19
    Description: Se realiza un breve resumen de estudios previos acerca de la circulación oceánica en el área del Pacífico Oriental Ecuatorial, haciendo énfasis en la zona frente a las costas del Ecuador. Posteriormente se analizan los datos de derivas y vientos tomados por el B/I ORION durante sus Cruceros de Investigación desde 1982, excluyendo aquellas observadas durante El Niño 82-83 y la información existente al oeste de 84° W. Del análisis de la información de derivas obtenidas durante casi todos los meses del año, se observa que el ramal oriental de la Corriente de Humboldt avanza con tendencia al norte bordeando las costas ecuatorianas, debido principalmente al empuje de los vientos alisios del SE. Este flujo denominado Corriente Costanera Ecuatoriana (CCE) gira hacia el noroeste a medida que se aleja de la costa. Por falta de información en ciertas zonas, se desconoce a ciencia cierta el límite norte del mismo, pero se observa que su presencia al norte de la equinoccial está influenciada por la zona Convergencia Intertropical (ZCIT). Durante la posición de la ZCIT en su extremo más meridional, un flujo proveniente del norte llega hasta las costas ecuatorianas ocasionado por la acción de los vientos alisios del NE. El Golfo de Guayaquil, siendo un sistema estuarino de gran extensión altera la normal trayectoria de la CCE hacia el norte, desviando la dirección de las corrientes en las zonas aledañas a su desembocadura, sin embargo, el flujo de la CCE logra atravesar la zona frente al Golfo y avanzar en su dirección norte.
    Description: Incluye ref.bibl., maps.
    Description: Published
    Keywords: Ocean currents ; Ocean circulation ; Intertropical convergence zone ; Ocean currents
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 6
    Publication Date: 2022-05-25
    Description: This is the first volume of a "final report" that summarizes, often in a speculative vein, what I have learned over the past 35 years or so about large-scale, low-frequency ocean currents, primarily with support from the Office of Naval Research (ONR). I was also fortunate to have been partially supported by the National Science Foundation and, during the preparation of this report, by the Clark Foundation. This report is meant to be an informal, occasionally anecdotal, state-of-the-art summary account of the World Ocean Circulation (WOC). Seemingly simple questions about how ocean currents behave, such as where various brands of sea water are coming from and going to, have been exciting and difficult research topics for many years. This report is not remotely about "all" of the WOC, it is simply a set of comments about what I have looked into. I believe that the results in this report, although presented in a personal way, are consistent with community wisdom. The report is intended to be readable by non-specialists who have a basic scientific/technical background, especially in other oceanographic areas or meteorology or physics or the geophysical disciplines, not just by specialists in physical oceanography. Anyone wishing to get spun up on the observational basis for the WOC could use this report and associated reference lists as a starting point. Volume I concentrates on the North Atlantic Ocean although there is preliminary discussion of global features. Highlights of this global summary are a new type of composite schematic picture of the World Ocean Circulation in its "upper layers" (Figure I-I) and new summaries (Figures 1-12, 21,91) of the global "thermohaline" circulation.
    Description: Funding was provided by the Office of Naval Research, Grant Nos. N00014-89-J-1039 and N00014-95-1-0356, and the Clark Foundation.
    Keywords: Global ocean circulation ; North Atlantic Circulation ; Ocean currents
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: 39418867 bytes
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  • 7
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-25
    Description: The Massachusetts Bays Program made bottom pressure and water velocity observations in Massachusetts and Cape Cod Bays during 1990 and 1991. In the Bays, the sea surface elevation appeared to rise and fall in phase with equal amplitudes at each diurnal or semidiurnal tidal frequency. There is some amplification in Boston and Provincetown harbors. The semidiurnal tides (particularly the M2 constituent) dominate. Massachusetts and Cape Cod Bays are part of the Gulf of Maine/Bay of Fundy system which is resonant near the semidiurnal frequency. This resonance amplifies the importance of the semidiurnal tides so that diurnal and higher harmonic tides become negligible. The sea level tides force currents which move with the same frequencies, but whose amplitudes are affected by the bathymetry. The strongest currents exist in the channel between Race Point and Stellwagen Bank where tidal currents exceed 1 knot. Analysis of current records for their tidal signal is complicated by internal tides which contaminate the records. These internal waves at tidal frequency exist on the stratification in the water column, and disappear during winter well-mixed times. At other times they must be considered as a signifcant source of energy for mixing and resuspension of sediments.
    Keywords: Tides ; Currents ; Internal waves
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: 3845643 bytes
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  • 8
    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
    Type: Article
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  • 9
    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
    Type: Article
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  • 10
    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): 2605–2623, doi:10.1175/2010JPO4132.1.
    Description: Steady scale-invariant solutions of a kinetic equation describing the statistics of oceanic internal gravity waves based on wave turbulence theory are investigated. It is shown in the nonrotating scale-invariant limit that the collision integral in the kinetic equation diverges for almost all spectral power-law exponents. These divergences come from resonant interactions with the smallest horizontal wavenumbers and/or the largest horizontal wavenumbers with extreme scale separations. A small domain is identified in which the scale-invariant collision integral converges and numerically find a convergent power-law solution. This numerical solution is close to the Garrett–Munk spectrum. Power-law exponents that potentially permit a balance between the infrared and ultraviolet divergences are investigated. The balanced exponents are generalizations of an exact solution of the scale-invariant kinetic equation, the Pelinovsky–Raevsky spectrum. A small but finite Coriolis parameter representing the effects of rotation is introduced into the kinetic equation to determine solutions over the divergent part of the domain using rigorous asymptotic arguments. This gives rise to the induced diffusion regime. The derivation of the kinetic equation is based on an assumption of weak nonlinearity. Dominance of the nonlocal interactions puts the self-consistency of the kinetic equation at risk. However, these weakly nonlinear stationary states are consistent with much of the observational evidence.
    Description: This research is supported by NSF CMG Grants 0417724, 0417732 and 0417466. YL is also supported by NSF DMS Grant 0807871 and ONR Award N00014-09-1-0515.
    Keywords: Waves ; Oceanic ; Internal waves ; Spectral analysis
    Repository Name: Woods Hole Open Access Server
    Type: Article
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