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
Filter
  • AMS (American Meteorological Society)  (3)
  • John Wiley & Sons  (1)
  • American Geophysical Union
  • Frontiers
  • IFM-GEOMAR
  • 2015-2019  (2)
  • 1995-1999
  • 1990-1994  (2)
  • 2017  (2)
  • 1991  (2)
Document type
Keywords
Publisher
Years
  • 2015-2019  (2)
  • 1995-1999
  • 1990-1994  (2)
Year
  • 1
    facet.materialart.
    Unknown
    Multidecadal Indian Ocean variability linked to the Pacific and implications for pre-conditioning Indian Ocean Dipole events (2017)
    AMS (American Meteorological Society)
    In:  Journal of Climate, 30 (5). pp. 1739-1751.
    Details
    Publication Date: 2020-02-06
    Description: The Indian Ocean has sustained robust surface warming in recent decades, but the role of multi-decadal variability remains unclear. Using ocean model hindcasts, characteristics of low-frequency Indian Ocean temperature variations are explored. Simulated upper-ocean temperature changes across the Indian Ocean in the hindcast are consistent with those recorded in observational products and ocean reanalyses. Indian Ocean temperatures exhibit strong warming trends since the 1950s limited to the surface and south of 30°S, while extensive subsurface cooling occurs over much of the tropical Indian Ocean. Previous work focused on diagnosing causes of these long-term trends in the Indian Ocean over the second half of the 20th Century. Instead, the temporal evolution of Indian Ocean subsurface heat content is shown here to reveal distinct multi-decadal variations associated with the Pacific Decadal Oscillation and the long-term trends are thus interpreted to result from aliasing of the low-frequency variability. Transmission of the multi-decadal signal occurs via an oceanic pathway through the Indonesian Throughflow and is manifest across the Indian Ocean centered along 12°S as westward propagating Rossby waves modulating thermocline and subsurface heat content variations. Resulting low-frequency changes in the eastern Indian Ocean thermocline depth are associated with decadal variations in the frequency of Indian Ocean Dipole (IOD) events, with positive IOD events unusually common in the 1960s and 1990s with a relatively shallow thermocline. In contrast, the deeper thermocline depth in the 1970s and 1980s is associated with frequent negative IOD and rare positive IOD events. Changes in Pacific wind forcing in recent decades and associated rapid increases in Indian Ocean subsurface heat content can thus affect the basin’s leading mode of variability, with implications for regional climate and vulnerable societies in surrounding countries.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1175/JCLI-D-16-0200.1
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
    facet.materialart.
    Unknown
    Seasonal transport variation in the western subtropical North Atlantic: Experiments with an eddy resolving model (1991)
    AMS (American Meteorological Society)
    In:  Journal of Physical Oceanography, 21 . pp. 1271-1289.
    Details
    Publication Date: 2020-08-04
    Description: A high-resolution model of the wind-driven and thermohaline circulation in the North and equatorial Atlantic Ocean is used to study the structure and variability of the boundary current system at 26°N, including the Florida Current, the Antilles Current, and the Deep Western Boundary Current (DWBC). The model was developed by Bryan and Holland as a Community Modeling Effort of the World Ocean Circulation Experiment. Subsequent experiments have been performed at IfM Kiel, with different friction coefficients, and different climatologies of monthly mean wind stress: Hellerman–Rosenstein (HR) and Isemer–Hasse (IH). The southward volume transports in the upper 1000 m of the interior Atlantic, at 26°N, are 25.0 Sv (Sv ≡ 106m3s−1) for HR, and 34.9 Sv for IH forcing, in good agreement with the transport from the integrated Sverdrup balance at this latitude (23.9 Sv for HR, 35.6 Sv for IH). The return flow of this wind-driven transport, plus the southward transport of the DWBC (6–8 Sv), is partitioned between the Florida Current and Antilles Current. With HR forcing, the transport through the Straits of Florida is 23.2 Sv; this increases to 29.1 Sv when the wind stresses of IH are used. The annual variation of the simulated Florida Current is very similar to previous, coarse-resolution models when using the same wind-stress climatology (HR); the annual range (3.4 Sv) obtained with HR forcing is strongly enhanced (6.3 Sv) with IH forcing. The meridional heat transport at 26°N, zonally integrated across the basin, is in phase with the Florida Current; its annual range increases from 0.44 PW (HR) to 0.80 PW (IH). The annual signal east of the Bahamas is masked by strong transport fluctuations on a time scale of O(100 days), caused by an instability of the Antilles Current. By averaging over several model years, an annual cycle is extracted, which is in phase with the wind stress curl over the western part of the basin.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1175/1520-0485(1991)021〈1271:STVITW〉2.0.CO;2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
    facet.materialart.
    Unknown
    Monthly mean wind stress and Sverdrup transport in the North Atlantic: A comparison of the Hellerman-Rosenstein and Isemer-Hasse climatologies (1991)
    AMS (American Meteorological Society)
    In:  Journal of Physical Oceanography, 21 . pp. 221-239.
    Details
    Publication Date: 2020-08-04
    Description: The monthly mean wind stress climatology of Hellerman and Rosenstein (HR) is compared with the climatology of Isemer and Hasse (IH), which represents a version of the Bunker atlas (BU) for the North Atlantic based on revised parameterizations. The drag coefficients adopted by IH are 21% smaller than the values of BU and HR, and the calculation of wind speed from marine estimates of Beaufort force (Bft) is based on a revised Beaufort equivalent scale similar to the scientific scale recommended by WMO. The latter choice significantly increases wind speed below Bft 8, and effectively counteracts the reduction of the drag coefficients. Comparing the IH stresses with HR reveals substantially enhanced magnitudes in the trade wind region throughout the year. At 15°N the mean easterly stress increases from about 0.9 (HR) to about 1.2 dyn cm−1 (IH). Annual mean differences are smaller in the region of the westerlies. In winter, the effect due to the reduced drag coefficient dominates and leads to smaller stress values in IH; during summer season the revision of the Beaufort equivalents is more effective and leads to increased stresses. Implications of the different wind stress climatologies for forcing the large-scale ocean circulation are discussed by means of the Sverdrup transport streamfunction (ψs): Throughout the subtropical gyre a significant intensification of ψs takes place with IH. At 27°N, differences of more than 10 Sv (1 Sv ≡ 106 m3 s−1) are found near the western boundary. Differences in the seasonality of ψs are more pronounced in near-equatorial regions where IH increase the amplitude of the annual cycle by about 50%. An eddy-resolving model of the North Atlantic circulation is used to examine the effect of the different wind stresses on the seasonal cycle of the Florida Current. The transport predicted by the numerical model is in much better agreement with observations when the circulation is forced by IH than by HR, regarding both the annual mean (29.1 Sv vs 23.2 Sv) and the seasonal range (6.3 Sv vs 3.4 Sv).
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1175/1520-0485(1991)021〈0221:MMWSAS〉2.0.CO;2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
    facet.materialart.
    Unknown
    Composition and variability of the Denmark Strait Overflow Water in a high-resolution numerical model hindcast simulation (2017)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 122 (2017): 2830–2846, doi:10.1002/2016JC012158.
    Description: The upstream sources and pathways of the Denmark Strait Overflow Water and their variability have been investigated using a high-resolution model hindcast. This global simulation covers the period from 1948 to 2009 and uses a fine model mesh (1/20°) to resolve mesoscale features and the complex current structure north of Iceland explicitly. The three sources of the Denmark Strait Overflow, the shelfbreak East Greenland Current (EGC), the separated EGC, and the North Icelandic Jet, have been analyzed using Eulerian and Lagrangian diagnostics. The shelfbreak EGC contributes the largest fraction in terms of volume and freshwater transport to the Denmark Strait Overflow and is the main driver of the overflow variability. The North Icelandic Jet contributes the densest water to the Denmark Strait Overflow and shows only small temporal transport variations. During summer, the net volume and freshwater transports to the south are reduced. On interannual time scales, these transports are highly correlated with the large-scale wind stress curl around Iceland and, to some extent, influenced by the North Atlantic Oscillation, with enhanced southward transports during positive phases. The Lagrangian trajectories support the existence of a hypothesized overturning loop along the shelfbreak north of Iceland, where water carried by the North Icelandic Irminger Current is transformed and feeds the North Icelandic Jet. Monitoring these two currents and the region north of the Iceland shelfbreak could provide the potential to track long-term changes in the Denmark Strait Overflow and thus also the AMOC.
    Description: Norwegian Research Council Grant Number: 231647
    Description: 2017-10-04
    Keywords: North Atlantic ; Denmark Strait ; Overflow ; Transport variability ; Overturning
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...