GLORIA

GEOMAR Library Ocean Research Information Access

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
    Keywords: Hochschulschrift ; Meso-Scale ; Numerisches Modell
    Description / Table of Contents: In der vorliegenden Arbeit werden zwei numerische Modelle vorgestellt,mit denen die Erzeugung und die hydrodynamische Instabilität mesoskaliger Fronten der potentiellen Vorticity (MPV-Fronten) in Ozean simuliert wird. (MOD)
    Type of Medium: Book
    Pages: XII, 188 S , graph. Darst , 30 cm
    Series Statement: Berichte aus dem Institut für Meereskunde an der Christian-Albrechts-Universität Kiel 156
    Language: German
    Note: Literaturverz. S. 181 - 188 , Mit engl. Zsfassung , Zugl.: Kiel, Univ., Diss. : 1986
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    Keywords: Hochschulschrift
    Type of Medium: Online Resource
    Pages: Online-Ressource (198 Seiten = 10 MB) , Graphen
    Language: German
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Keywords: Hochschulschrift ; Meso-Scale ; Numerisches Modell
    Type of Medium: Online Resource
    Pages: Online-Ressource (202 Seiten, 5 MB) , Diagramme
    Series Statement: Berichte aus dem Institut für Meereskunde an der Christian-Albrechts-Universität Kiel 156
    Language: German
    Note: Zusammenfassung in deutscher und englischer Sprache
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    facet.materialart.
    Unknown
    PANGAEA
    In:  Bundesamt für Seeschiffahrt und Hydrographie, Hamburg
    Publication Date: 2024-02-02
    Keywords: 06MT22_5; CT; DATE/TIME; Depth, bathymetric; LATITUDE; LONGITUDE; M22/5; M22/5-track; Meteor (1986); South Atlantic; Swath-mapping system Atlas Hydrosweep DS; Underway cruise track measurements; WOCE; World Ocean Circulation Experiment
    Type: Dataset
    Format: text/tab-separated-values, 2610 data points
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 5
    facet.materialart.
    Unknown
    AMS (American Meteorological Society)
    In:  Journal of Physical Oceanography, 23 (8). pp. 1638-1646.
    Publication Date: 2018-03-23
    Description: New light is shed on Worthington's concept of the North Atlantic circulation, postulating the existence of two anticyclonic gyres. This concept, which seems to have been laid to rest in the last decade, has now been reinforced by the results of a simple linear Sverdrup circulation model yielding a band of westward transport all across the North Atlantic at about the Azores latitude. This narrow band is called the Azores Countercurrent (AzCC) and matches the position of westward flow required by Worthington's “northern gyre.” An anomaly in the meridional change of the wind-stress curl in the eastern North Atlantic has been identified as the driving mechanism. A comparison with observations shows that the AzCC is verified in many analyses of historical datasets and synoptic surveys. A lack of the AzCC in other analyses is probably due to missing meridional sections, strong smoothing, and the superimposed Ekman flow close to the sea surface directed to the southeast. The AzCC has not been verified in low-resolution general circulation models applying simplified wind-stress fields and large friction coefficients, but there is evidence for its existence in recent high-resolution models driven by realistic wind stresses. Based on these findings, a new pattern for the wind-driven upper ocean circulation of the midlatitude North Atlantic is presented.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 6
    facet.materialart.
    Unknown
    AMS (American Meteorological Society)
    In:  Journal of Physical Oceanography, 24 (5). pp. 928-948.
    Publication Date: 2018-08-13
    Description: Observations of upper-ocean western boundary current (WBC) transports reveal asymmetries between the Northern and the Southern Hemispheres of the Atlantic Ocean. To find out what mechanism might cause these asymmetries the linearized steady-state vorticity equation is applied to the interior of a layer of constant thickness representing the upper Atlantic Ocean. WBC transports are then required to balance the interior volume flux deficit. The ocean is forced by climatological wind stress at the surface; thermohaline forcing is introduced by vertical motion at the lower boundary. A series of model runs using selected combinations of different basin geometries, wind stress fields, and thermohaline forcing patterns yields the following results: asymmetries of WBC transports cannot be explained by the topography shape of coastlines. The wind stress causes 12 Sv (Sv ≡ 1 × 106 m3 s −1) cross-equatorial transport to the north but it cannot account for the other WBC asymmetries. These can be explained by superimposing a thermohaline flow component to the wind-driven circulation. The best agreement with observations could be obtained from a model run driven by a sinking rate of 20 Sv in the northern North Atlantic and 4 Sv in the Weddell Sea compensated by 15 Sv return flow from other oceans via the Agulhas Current or Drake Passage and uniform upwelling of 9 Sv in the Atlantic. In tropical and subtropical latitudes this run reproduces all observed asymmetries, but in subpolar latitudes the model fails. Further conclusions can be drawn from the model results. (i) Up to 20 Sv northward transport of Antarctic Intermediate Water is needed at about 10°S to explain the difference of modeled transports and observations. For the same reasons an Antilles Current of up to 16 Sv is required. (ii) The major part of the northward heat transport in the North Atlantic has to occur via the tropical countercurrents and the North Equatorial Current. Only less than 7 Sv take the shortest way to the Caribbean via the Guyana Current. (iii) Fifty-six percent of the Florida Straits transport is wind driven.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 7
    facet.materialart.
    Unknown
    AMS (American Meteorological Society)
    In:  Journal of Physical Oceanography, 22 (11). pp. 1257-1273.
    Publication Date: 2018-03-16
    Description: Results of a three-dimensional primitive equation model are presented simulating turbulent mesoscale motions in the seasonal thermocline on an f plane. The model is based on a hybrid vertical coordinate scheme and conserves isopycnic potential vorticity. Mesoscale turbulence is modeled in terms of an unstable potential vorticity front. The model integration starts from a purely zonal, 60-km-wide geostrophically balanced jet, on which is superimposed a small initial perturbation. The most unstable mode exhibits a wavelength of 85 km and is driven by a mixed type of instability. Characteristic dynamical ingredients of the wave are enhanced cyclonic and anticyclonic relative vorticity in the troughs and the ridges, respectively, due to the curvature of the flow. Vertical motion of up to 10 m d−1 occurring downstream of the ridges (downwelling) and downstream of the troughs (upwelling) is driven by geostrophic advection of relative vorticity. The contrast of static stability across the front is changing during amplification of the instability: in troughs the stability is decreasing whereas in ridges it is increasing. The density field exhibits local anomalies of the isopycnals' depths (bumps) due to the ageostrophic cross-jet advection of potential vorticity streamers wound up in cyclones and anticyclones. Locally, the potential vorticity gradients are enhanced, creating a multiple front structure. The model results support observations and findings of earlier atmospheric and oceanic models. It is emphasized that mesoscale turbulent structures may have a profound influence on primary productivity, mixed-layer, and internal wave dynamics.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 8
    facet.materialart.
    Unknown
    AGU (American Geophysical Union)
    In:  Journal of Geophysical Research: Oceans, 97 (C1). pp. 703-715.
    Publication Date: 2017-09-26
    Description: The Guinea Dome is a permanent, quasi-stationary feature on the eastern side of the thermal ridge extending zonally across the tropical North Atlantic. The dome is a part of the large-scale near-surface flow fields associated with the North Equatorial Current, the North Equatorial Countercurrent and the North Equatorial Undercurrent. In the present study, historical and recently obtained hydrographic data are combined to investigate the thermohaline structure and geostrophic flow field in the vicinity of the dome. It is shown that the Guinea Dome exists throughout the year both in subthermocline and thermocline layers, that it has a corresponding cyclonic geostrophic flow, and that seasonal changes occur with respect to its vertical structure, horizontal extent, and position. The observational results are then compared with simulations from a general circulation model of the tropical Atlantic. A seven-year simulation forced by observed monthly winds is run to compute a monthly climatology. The model adequately simulates the Guinea Dome with respect to its structure, flow field, and seasonal variability.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 9
    facet.materialart.
    Unknown
    AGU (American Geophysical Union)
    In:  Journal of Geophysical Research: Oceans, 103 (C10). 21,469-21,479.
    Publication Date: 2018-04-30
    Description: Mechanical energy terms are calculated from moored current meter data in the Cape Verde Frontal Zone (about 20°N, 25°W) and compared with those derived from a mesoscale model of this frontal region. The model is of the Bleck and Boudra [1981] type with isopycnal coordinates. An initially zonal jet, representing the Canary Current, is allowed to develop under the influence of baroclinic and barotropic instability processes. We find reasonable agreement in magnitudes, somewhat smaller in the model, and similar distributions in the vertical. This leads to the conclusion that the energy transfer terms from the model can be expected to be sufficiently close to reality. Determination of the transfer terms confirms that the energy transfer in the zone is dominated by baroclinic instability processes while barotropic instability is of minor importance. Average baroclinic instability energy transfer terms reach values of 2–3 μW m−3 in the pycnocline. Peak layer mean values are of the order 10 μW m−3. It is shown that the spatial distribution of active transfer regions is closely related to the structure of the transient eddy field in the frontal zone and that strong instability processes are restricted to the pycnocline.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 10
    facet.materialart.
    Unknown
    In:  (PhD/ Doctoral thesis), Christian-Albrechts-Universität Kiel, Kiel, Germany, 188 pp . Berichte aus dem Institut für Meereskunde an der Christian-Albrechts-Universität Kiel, 156 . DOI 10.3289/ifm_ber_156 〈http://dx.doi.org/10.3289/ifm_ber_156〉.
    Publication Date: 2014-10-15
    Type: Thesis , NonPeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...