GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Dispersion of passive tracers in model flows: effects of the parametrization of small-scale processes (1996)
    Springer
    Annales geophysicae 14 (1996), S. 476-484 
    Details
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A set of numerical experiments is presented, in which we study the dynamics of passive particles advected by given two-dimensional velocity fields and perturbed by a non-white noise with a characteristic time 〈tau〉. Data and model results have shown that this kind of random perturbation is able to represent subgridscale processes for upper ocean mesoscale turbulence for regions of the world ocean where turbulence can be assumed to be homogeneous. Extensive computations in different fields characterized by cell-like structure, both stationary and time-dependent, representing very idealized geophysical flow situations, show that the presence of a finite correlation time scale does lead to enhanced or arrested dispersion, depending on the considered flow; however, it does not seem to affect the gross qualitative behaviour of the dispersion processes, which is primarily affected by the large-scale velocity field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-996-0476-x
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Modelling of dispersion processes in a tide-forced flow (1999)
    Springer
    Hydrobiologia 393 (1999), S. 19-24 
    Details
    ISSN: 1573-5117
    Keywords: passive tracer ; advection-diffusion ; tidal flows ; residence times
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dispersion processes in semi-enclosed basins where the flow is mainly forced by the tidal motion are studied by means of an advection–diffusion model. A parametric study was performed by varying the diffusion coefficient, the type of boundary conditions at the open boundaries of the basin and the initial position of the release. We analyzed the dependence of the initial and the asymptotic phases of the dispersion process and of the residence time in the basin, on the above parameters, and on the flow patterns corresponding to different hydrodynamic scenarios. We showed that the tidal forcing produces, on the average, a stationary diffusion process. Differences with dispersion in a stationary unidirectional flow were assessed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003508925747
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    facet.materialart.
    Unknown
    Dynamics of Transport, Accumulation, and Export of Plastics at Oceanic Fronts (2022)
    Springer
    Details
    Publication Date: 2022-04-29
    Description: Every year, vast quantities of plastic debris arrive at the ocean surface. Nevertheless, our understanding of plastic movements is largely incomplete and many of the processes involved with the horizontal and vertical displacement of plastics in the ocean are still basically unknown. In this chapter we review the dynamics associated with the transport of plastics and other pollutants at oceanic fronts. Fronts had been historically defined as simple barriers to exchange, but here we show that the role of these structures in influencing the transport of plastics is more complex. The tools used to investigate the occurrence of frontal structures at various spatial scales are reviewed in detail, with a particular focus on their potential applications to the study of plastic pollution. Three selected case studies are presented to better describe the role of fronts in favoring or preventing plastic exchanges: the large-scale Antarctic Circumpolar Current, a Mediterranean mesoscale front, and the submesoscale fronts in the Gulf of Mexico. Lastly, some aspects related to the vertical subduction of plastic particles at oceanic fronts are discussed as one of the most promising frontiers for future research. The accumulation of floating debris at the sea surface is mainly affected by the horizontal components of frontal dynamics. At the same time, vertical components can be relevant for the export of neutrally buoyant particles from the surface into the deep sea. Based on these evidences, we propose that submesoscale processes can provide a fast and efficient route of plastic transport within the mixed layer, while mesoscale instabilities and associated vertical velocities might be the dominant mechanism to penetrate the deeper ocean on slower but broader scales. We conclude that given the ubiquitous presence of fronts in the world’s ocean, their contribution to the global plastic cycle is probably not negligible and the role of these processes in vertically displacing neutrally buoyant microplastics should be investigated in more detail.
    Type: Book chapter , NonPeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Book chapter
  • 4
    facet.materialart.
    Unknown
    Western Ross Sea continental slope gravity currents (2009)
    Elsevier
    In:  Deep Sea Research Part II: Topical Studies in Oceanography, 56 (13-14). pp. 796-817.
    Details
    Publication Date: 2020-08-05
    Description: Antarctic Bottom Water of the world ocean is derived from dense Shelf Water that is carried downslope by gravity currents at specific sites along the Antarctic margins. Data gathered by the AnSlope and CLIMA programs reveal the presence of energetic gravity currents that are formed over the western continental slope of the Ross Sea when High Salinity Shelf Water exits the shelf through Drygalski Trough. Joides Trough, immediately to the east, offers an additional escape route for less saline Shelf Water, while the Glomar Challenger Trough still farther east is a major pathway for export of the once supercooled low-salinity Ice Shelf Water that forms under the Ross Ice Shelf. The Drygalski Trough gravity currents increase in thickness from ∼100 to ∼400 m on proceeding downslope from ∼600 m (the shelf break) to 1200 m (upper slope) sea floor depth, while turning sharply to the west in response to the Coriolis force during their descent. The mean current pathway trends ∼35° downslope from isobaths. Benthic-layer current and thickness are correlated with the bottom water salinity, which exerts the primary control over the benthic-layer density. A 1-year time series of bottom-water current and hydrographic properties obtained on the slope near the 1000 m isobath indicates episodic pulses of Shelf Water export through Drygalski Trough. These cold (〈−1 °C), salty (〉34.75) pulses correlate with strong downslope bottom flow. Extreme examples occurred during austral summer/fall 2003, comprising concentrated High Salinity Shelf Water (−1.9 °C; 34.79) and approaching 1.5 m s−1 at descent angles as large as ∼60° relative to the isobaths. Such events were most common during November–May, consistent with a northward shift in position of the dense Shelf Water during austral summer. The coldest, saltiest bottom water was measured from mid-April to mid-May 2003. The summer/fall export of High Salinity Shelf Water observed in 2004 was less than that seen in 2003. This difference, if real, may reflect the influence of the large iceberg C-19 over Drygalski Trough until its departure in mid-May 2003, when there was a marked decrease in the coldest, saltiest gravity current adjacent to Drygalski Trough. Northward transport of cold, saline, recently ventilated Antarctic Bottom Water observed in March 2004 off Cape Adare was ∼1.7 Sv, including ∼0.4 Sv of High Salinity Shelf Water.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.dsr2.2008.10.037
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
    facet.materialart.
    Unknown
    Energetic plumes over the western Ross Sea continental slope (2004)
    AGU (American Geophysical Union)
    In:  Geophysical Research Letters, 31 (21). L21302.
    Details
    Publication Date: 2018-03-21
    Description: Rapid descent of dense Drygalski Trough (western Ross Sea, Antarctica) shelf water over the continental slope, within 100 to 250 m thick benthic plumes, is described. Speeds of up to 1.0 m/s are recorded flowing at an average angle of 35° to the isobaths, entraining ambient Lower Circumpolar Deep Water en route. This process is predominant in determining the concentration and placement of the shelf water injected into the deep sea as a precursor Antarctic Bottom Water. Nonetheless, a 4-hour duration pulse of undiluted shelf water was observed at depth (1407 m) directly north of the Drygalski Trough, moving at around 90 degrees to isobaths, and at a speed of 1.4 m/s. Thus the export of Ross Sea shelf water to the deep sea is accomplished within plumes descending at moderate angle to isobaths, punctuated by rapid downhill cascades.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1029/2004GL020785
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
    facet.materialart.
    Unknown
    Investigating the fresh-water inflow through the eastern gate in the Ross Sea (2023)
    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Details
    Publication Date: 2023-07-25
    Description: The production of Antarctic Bottom Water (AABW) is a crucial factor in determining the strength of the Meridional Overturning Circulation, and therefore plays a significant role in the ocean's contribution to the global climate. AABW is primarily formed in the Ross and Weddell Seas, with unique thermohaline characteristics. In recent years, a negative decadal salinity trend has been observed in the Southern Ocean's Pacific sector, related to AABW modification. Correspondingly in the Ross Sea, observations have indicated changes in the thermohaline characteristics of the shelf waters, precursors of the AABW, since 1995. The significant freshening in the western Ross Sea, where AABW is formed and spreads to fill the Pacific Ocean's deep basins, was attributed to the inflow of waters from West Antarctica where a dramatic melting of glaciers is occurring. To determine the freshwater inflow from West Antarctica and the role of these waters in the salinity field variability, a dedicated oceanographic cruise was carried out during austral summer 2020 in the eastern sector of the Ross Sea. Additionally, a section of the same CTD grid was repeated during January 2021. Using physical data from the CTD and LADCP casts, glider deployment and drifters, we estimated water mass characteristics and dynamical features. Eventually, discrete sea water sampling for chemical analyses (nutrients, carbonate system, trace metals, persistent organic compounds) has been carried out to provide new information about the biogeochemistry of the area and origin of the water masses.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    GFZ OAI
  • 7
    facet.materialart.
    Unknown
    New insights into winter-time dynamics of the Ross Sea: an analysis of grounded Argo floats under ice (2023)
    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Details
    Publication Date: 2023-08-09
    Description: The Ross Ice Shelf (RIS) floats over the southern sector of the Ross Sea creating beneath a crucial area for ocean-ice interactions, known as the cavity. This area is characterized by the formation of Ice Shelf Water (ISW) as well as the intrusion of warm water, which is the main driver of basal melting and ice shelf calving. Ocean-driven basal melting and calving are the predominant causes of ice-shelf buttressing losses and the ice discharge that directly affects the global sea level. While the RIS is not considered to be under threat from the on-shelf intrusion of warm Circumpolar Deep Water (CDW), dense High Salinity Shelf Water (HSSW) and seasonally warmed Antarctic Surface Water (AASW) are expected to cause significant basal melting. The RIS northwest sector, which is directly exposed to solar-heated AASW, sees melt rates that nearly triple during the summer months. In this work, we present unprecedented thermohaline observations from Argo floats close to the north-western sector of the RIS during 2020-2022. Data from the floats provide insights into the year-around water mass structure along and even under the RIS. The continuous under-ice profiles made it possible to observe the complete cycle of water column change during seasonal transitions, the formation of HSSW in the RIS polynya as well as the outflow of ISW. Moreover, one Argo float spent 6 months under the RIS, collecting data directly at the sea-ice interface and capturing the intrusion of warm surface waters into the shelf cavity during the summer.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    GFZ OAI
  • 8
    facet.materialart.
    Unknown
    New insights into long-term trends and extreme events in the Tyrrhenian Sea (2023)
    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Details
    Publication Date: 2023-05-10
    Description: The Mediterranean Sea is well-known for its sensitivity to climate change, leading to extensive efforts in monitoring the basin as a whole. However, the Mediterranean is composed of individual sub-basins that exhibit different roles in its conveyor belt’s function. Additionally, impacts on societies and ecosystems have been shown to depend primarily on local manifestation of global-scale changes. Thus, sufficient risk assessment and the development of feasible adaptation strategies require regional studies, especially in sub-basins with high population density along their coastlines. The Tyrrhenian basin, one of the main mixing areas of the Mediterranean, is among the most densely populated semi-enclosed basins, yet it remains the least investigated. This work addresses this issue and provides new regional products, implementing information about the state, long-term variability, and changes in the surface and sub-surface layers of the Tyrrhenian Sea, while considering the potential role of local forcing as well as large-scale climatic patterns. Essential surface monitoring indicators, such as sea surface temperature, sea level anomaly, geostrophic currents, and air-sea interactions, were assessed using satellite, reanalysis, and in-situ data over the last four decades. Corresponding sub-surface indicators, including ocean heat and salt contents and water mass physical properties, were also computed based on more than 750000 hydrographic stations. A dedicated website was created to distribute these indicators, the regional dataset and the corresponding climatologies in order to respond to the increasing needs for directly usable regional products and to provide a reference baseline for the Tyrrhenian Sea.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    GFZ OAI
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...