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6 pages, 4 figures, Intensive sampling of the deep Mediterranean outflow 70 km W of the Strait of Gibraltar reveals a strong, tidally modulated gravity current embedded with large-amplitude oscillations and energetic turbulence. The flow appears to be hydraulically controlled at a small topographic constriction, with turbulence and internal waves varying together and increasing dramatically downstream of the choke point. These data suggest that a significant fraction of energy dissipation, mixing, and entrainment stress in gravity currents may occur in localized regions controlled by time-varying flow interactions with fine-scale topography. These findings highlight the important role of processes that are not resolved by global climate models (GCMs), which do not contain tides or mixing due to fine-scale topographic interactions. © 2012. American Geophysical Union. All Rights Reserved, This work was supported by the U.S. National Science Foundation, grants OCE-0825287, OCE-0825297, and the Spanish Ministerio de Ciencia e Innovación, grants CTM2008-06438-C02-01 and CTM2008-03422-E/MAR

I Encuentro de la Oceanografía Física Española (EOF), 13-15 de octubre 2010, Barcelona, The Straits of Gibraltar play an important role in the context of the global thermohaline circulation: dense, salty Mediterranean Water (MW) exiting through the straits facilitates the subduction and formation of deep Arctic Basin Waters, which constitute a major component of the North Atlantic Deep Water and the global conveyor belt. This presentation describes the results of a fifteen‐day long cruise realized on July 2009 by the BIO 'García del Cid' in the context of the project “Memory of Climate ‐ Meridional Overturning Circulation” (MOC‐MOC) on a 35 by 25 Km region centered at 35.85°N, 6.4°W. The aim of the study is to provide an account of the long‐period mass and salinity fluxes west of the Straits of Gibraltar, and the relative importance of mixing, frictional processes, tides, geostrophic adjustment, centrifugal forces and topographic steering. In order to obtain the general spatial distribution of the temperature and salinity fields five principal transects (22 stations) were realized perpendicular to the assumed path of the Mediterranean Outflow. A more detailed survey, including yo‐yo CTD transects, two moorings and two 24‐hour vertical time series, focused on a square box roughly one third of the length of the exterior domain, located at 35.75°N, 6.35°W. In total 418 CTD casts were performed. Property fields indicate that the trajectory of the MW Outflow is driven by the equilibrium between topographic steering and Coriolis forces. Diapycnal mixing develops as a result of the interplay between tidal currents, hydraulic jumps and internal waves generated in regions with strong bathymetry drops

Deep-water Circulation: Processes & Products. International Congress 16-18 june 2010, Baiona, Pontevedra, Spain, [EN] Deep-water circulation is a critical part of the global conveyor belt that regulates Earth's climate. The bottom current component of this circulation is hugely significant in shaping the deep seafloor, through erosion, transport and deposition. As a result a great variety of depositional and erosive features are developed, including a range of different drifts, sediment waves, moats, furrows, and abraded surfaces. The Baiona Congress will be focused specifically on processes and deposits related to bottom-water circulation, [ES] La circulación de aguas profundas es una parte crítica del sistema global que regula el clima de la Tierra. Las corrientes del fondo, componentes de esta circulación, son enormemente significativas para dar forma al fondo marino, mediante la erosion, trasporte y sedimentación. Como resultado, se desarrollan una gran variedad de sedimentos y rasgos erosivos, incluyendo un rango de diferentes flujos, olas de sedimentos, fosos, surcos y superficies desgastadas. El Congreso de Baiona se centrará específicamente en los procesos y los sedimentos relacionados con la circulación de aguas del fondo marino

Quasi-synoptic, three-dimensional surveys of physical and optical variability characterize the mesoscale features that dominate the Northern and Central Adriatic, following their response to strong forcing events. During winter (February), sampling emphasized the response to episodic Bora wind events. Although springtime (May) measurement program was designed to sample during the Po River spring freshette, freshwater discharge rates were more than a standard deviation below the 12-year mean and winds remained weak throughout the survey period, leading to a study of weakly forced dynamics in a strongly stratified, shallow water regime. Wintertime sampling included surveys of a strong shallow-water front and a prominent extension of the Po River plume. The surveys captured the evolution of a nearly vertical, compensated front that tilts as the strong Bora winds weaken. A broad survey of the northern basin characterized the structure of a Bora-driven Po plume extension and reveals cyclonic (anticyclonic) circulation to the north (south) of the plume, consistent with the response found in previous numerical experiments.

Quasi-synoptic, three-dimensional surveys of physical and optical variability characterize the mesoscale features that dominate the Northern and Central Adriatic, following their response to strong forcing events. During winter (February), sampling emphasized the response to episodic bora wind events. Although springtime (May) measurement program was designed to sample during the Po River spring freshette, freshwater discharge rates were more than a standard deviation below the 12-year mean and winds remained weakthroughout the survey period, leading to a study of weakly forced dynamics in a strongly stratified, shallow water regime. Wintertime sampling included survays of a strong shallow-water front and a prominent extension of the Po River plume. The surveys captured the evolution of a nearly vertical, compensated front that tilts as the strong bora winds weaken. A broad survey of the northern basin characterized the structure of a bora-driven po plume extension and reveals cyclonic (anticyclonic) circulation to the north (south) of the plume, consistent with the response found in previous numerical experiments.

Quasi-synoptic, three-dimensional surveys of physical and optical variability characterize the mesoscale features that dominate the Northern and Central Adriatic, following their response to strong forcing events. During winter (February), sampling emphasized the response to episodic bora wind events. Although spring time (May) measurement program was designed to sample during the Po River spring freshette, freshwater discharge rates were more than a standard deviation below the 12-year mean and winds remained weak throughout the survey period, leading to a study of weakly forced dynamics in a strongly stratified, shallow water regime. Wintertime sampling included surveys of a strong shallow-water front and a prominent extension of the Po River plume. The surveys captured the evolution of the strong bora winds weaken. A broad survey of the northern basin characterized the structure of a bora-driven Po plume extension and reveals cyclonic (anticyclonic) circulation to the north (south) of the plume, consistent with the response found in previous numerical experiments.

Oceanographic measurements by groups from the Federal Republic of Germany contributed mainly to the C-Scale Experiment (centered at 9° N, 23° W) and the Equatoria1 Experiment. In this paper the data are presented that were obtained from the moorings F 1 and F 2 in the C-area. After a short discussion of instrument problems, data processing and statistical analysis, the data are presented graphically as time series, progressive vector diagrams, frequency distributions and spectra of horizontal kinetic energy and of temperature variance.

Berichte aus dem Institut für Meereskunde an der Christian-Albrechts-Universität Kiel No 19

OceanRep OceanRep Home Contact Quick Search Simple Search Advanced Search Browse Author Research division Document type Year Course of Study Latest Peer-reviewed Articles All About us GEOMAR Library Open Access Policies Statements Help FAQs Statistics Directions | Contact | Sitemap | Imprint Zur Kinematik eines stochastischen Feldes interner Wellen in einer Scherströmung. Logged in as Barbara Schmidt Manage depositsManage recordsManage shelvesProfileSaved searchesReviewAdminLogout - Tools Peters, Hartmut (1981) Zur Kinematik eines stochastischen Feldes interner Wellen in einer Scherströmung. (Doctoral thesis/PhD), Christian-Albrechts-Universität Kiel, Kiel, Germany, 118 pp. [img] Text Diss. 1981 Peters, H.pdf - Published Version Restricted to Registered users only Download (7Mb) Abstract Für die im Atlantik im Bereich des Äquatorialen Gegenstroms während GATE beobachtete mittlere Schichtung und Scherströmung werden vertikale Eigenschwingungen (Moden) und Dispersionskurven hochfrequenter (0.3 bis 15 cph) interner Wellen berechnet. Ein spektrales Modell der Kinematik freier, linearer interner Wellen wird durch die stochastische Überlagerung so gewonnener Moden erzeugt. Modellrechnungen werden zu Vergleichs- und Testzwecken für einfache Grundzustände (N 2 = const.; u = const.) durchgeführt. Die den Verhältnissen während GATE entsprechenden Rechnungen ergeben folgende Resultate: In den Energiespektren wird eine Schulter bei Frequenzen zwischen 1.5 und 4 cph beobachtet, die einen nicht unbeträchtlichen Teil der Gesamtenergie des Wellenfeldes repräsentiert. Diese Schulter kann im wesentlichen nicht durch kinematische Effekte erklärt werden, sie muß dynamische Ursachen haben. Im Frequenzbereich 1.5 bis 4 cph wird das Wellenfeld praktisch ausschließlich von der ersten Mode beherrscht. Nach den Beobachtungen sind die Wellen überwiegend gegen die mittlere Strömung gerichtet. Zur Erklärung dessen müssen sowohl dynamische als auch kinematische Effekte herangezogen werden. Das beobachtete Maximum der Kohärenz zwischen Strömung in der Deckschicht und Temperatur in der Sprungschicht zwischen 1. 5 und 4 cph ist prinzipiell der Kinematik des Systems zuzuschreiben. Die Skalen des Wellenzahlspektrums, die sich aus der Anpassung des Modells an die Daten ergeben, sind derart, daß nur ein Teil der Anisotropie des Systems von Moden und Dispersionskurven wirksam wird. Die Vertikalstruktur der beobachteten Strömungsfluktuationen kann mit dem Modell nicht vollständig beschrieben werden. Das Modell wird kritisch diskutiert.

Berichte aus dem Institut für Meereskunde an der Christian-Albrechts-Universität Kiel No 82

Berichte aus dem Institut für Meereskunde an der Christian-Albrechts-Universität Kiel No 22

This paper presents a compilation of the data sets obtained by CTDs and profiling current meters on board the ships "Meteor" and "Planet" during GATE in the B- and C-Scale Areas (7°-10 °N, 22°-25°W, June 17 to September 24, 1974). The bulk of the CTD data is displayed in the form of isopleths. Selected sets of profiles, outlining special phenomena observed, and profiles of the mean and standard deviation of temperature and salinity are given additionally. Besides examples of actual current profiles, isopleths of the 25 hour mean current components, and isopleths of the vertical shear are presented. The mean current components and their standard deviations are also displayed. Time series presented are suitable for comparison with moored current measurements. The presentation of the data is preceded by a summary of the editing procedures and by a discussion of the data quality.