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
Document type
Language
Years
back to result list
1
Online Resource
Online Resource
Variability in the subtropical-tropical cells and its effect on near-surface temperature of the equatorial Pacific: a model study (2008)
Details Availability
In: Ocean science, Katlenburg-Lindau : Copernicus Publ., 2005, 4(2008), Seite 73-88, 1812-0792
In: volume:4
In: year:2008
In: pages:73-88
Description / Table of Contents: A set of experiments utilizing different implementations of the global ORCA-LIM model with horizontal resolutions of 2°, 0.5° and 0.25° is used to investigate tropical and extra-tropical influences on equatorial Pacific SST variability at interannual to decadal time scales. The model experiments use a bulk forcing methodology building on the global forcing data set for 1958 to 2000 developed by Large and Yeager (2004) that is based on a blend of atmospheric reanalysis data and satellite products. Whereas representation of the mean structure and transports of the (sub-)tropical Pacific current fields is much improved with the enhanced horizontal resolution, there is only little difference in the simulation of the interannual variability in the equatorial regime between the 0.5° and 0.25° model versions, with both solutions capturing the observed SST variability in the Nino3-region. The question of remotely forced oceanic contributions to the equatorial variability, in particular, the role of low-frequency changes in the transports of the Subtropical Cells (STCs), is addressed by a sequence of perturbation experiments using different combinations of fluxes. The solutions show the near-surface temperature variability to be governed by wind-driven changes in the Equatorial Undercurrent. The relative contributions of equatorial and off-equatorial atmospheric forcing differ between interannual and longer, (multi-) decadal timescales: for the latter there is a significant impact of changes in the equatorward transport of subtropical thermocline water associated with the lower branches of the STCs, related to variations in the off-equatorial trade winds. A conspicuous feature of the STC variability is that the equatorward transports in the interior and along the western boundary partially compensate each other at both decadal and interannual time scales, with the strongest transport extrema occurring during El Nino episodes. The behaviour is rationalized in terms of a wobbling in the poleward extents of the tropical gyres, which is manifested also in a meridional shifting of the bifurcation latitudes of the North and South Equatorial Current systems.
Type of Medium: Online Resource
ISSN: 1812-0792
Language: English
Location Call Number Limitation Availability
BibTip Others were also interested in ...
GEOMAR CATALOGUE
Link to Library Catalog
get availability status
Associated Volumes
  • 2
    Online Resource
    Online Resource
    Optical tools for ocean monitoring and research (2009)
    Details Availability
    In: Ocean science, Katlenburg-Lindau : Copernicus Publ., 2005, 5(2009), 4, Seite 661-684, 1812-0792
    In: volume:5
    In: year:2009
    In: number:4
    In: pages:661-684
    Description / Table of Contents: Requirements for understanding the relationships between ocean color and suspended and dissolved materials within the water column, and a rapidly emerging photonics and materials technology base for performing optical based analytical techniques have generated a diverse offering of commercial sensors and research prototypes that perform optical measurements in water. Through inversion, these tools are now being used to determine a diverse set of related biogeochemical and physical parameters. Techniques engaged include measurement of the solar radiance distribution, absorption, scattering, stimulated fluorescence, flow cytometry, and various spectroscopy methods. Selective membranes and other techniques for material isolation further enhance specificity, leading to sensors for measurement of dissolved oxygen, methane, carbon dioxide, common nutrients and a variety of other parameters. Scientists are using these measurements to infer information related to an increasing set of parameters and wide range of applications over relevant scales in space and time.
    Type of Medium: Online Resource
    Pages: Ill., graph. Darst
    ISSN: 1812-0792
    URL: http://www.ocean-sci.net/5/661/2009/os-5-661-2009.html
    Language: English
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    GEOMAR CATALOGUE
    Link to Library Catalog
    get availability status
  • 3
    Online Resource
    Online Resource
    A chemical ionization mass spectrometer for continuous underway shipboard analysis of dimethylsulfide in near-surface seawater (2009)
    Details Availability
    In: Ocean science, Katlenburg-Lindau : Copernicus Publ., 2005, 5(2009), 4, Seite 537-546, 1812-0792
    In: volume:5
    In: year:2009
    In: number:4
    In: pages:537-546
    Description / Table of Contents: A compact, low-cost atmospheric pressure, chemical ionization mass spectrometer ("mini-CIMS") has been developed for continuous underway shipboard measurements of dimethylsulfide (DMS) in seawater. The instrument was used to analyze DMS in air equilibrated with flowing seawater across a porous Teflon membrane equilibrator. The equilibrated gas stream was diluted with air containing an isotopically-labeled internal standard. DMS is ionized at atmospheric pressure via proton transfer from water vapor, then declustered, mass filtered via quadrupole mass spectrometry, and detected with an electron multiplier. The instrument described here is based on a low-cost residual gas analyzer (Stanford Research Systems), which has been modified for use as a chemical ionization mass spectrometer. The mini-CIMS has a gas phase detection limit of 220 ppt DMS for a 1 min averaging time, which is roughly equivalent to a seawater DMS concentration of 0.1 nM DMS at 20°C. The mini-CIMS has the sensitivity, selectivity, and time response required for underway measurements of surface ocean DMS over the full range of oceanographic conditions. The simple, robust design and relatively low cost of the instrument are intended to facilitate use in process studies and surveys, with potential for long-term deployment on research vessels, ships of opportunity, and large buoys.
    Type of Medium: Online Resource
    Pages: graph. Darst
    ISSN: 1812-0792
    URL: http://www.ocean-sci.net/5/537/2009/
    DOI: 10.5194/os-5-537-2009
    Language: English
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    GEOMAR CATALOGUE
    Link to Library Catalog
    get availability status
  • 4
    Online Resource
    Online Resource
    Relating Agulhas leakage to the Agulhas Current retroflection location (2009)
    Details Availability
    In: Ocean science, Katlenburg-Lindau : Copernicus Publ., 2005, 5(2009), 4, Seite 511-521, 1812-0792
    In: volume:5
    In: year:2009
    In: number:4
    In: pages:511-521
    Description / Table of Contents: The relation between the Agulhas Current retroflection location and the magnitude of Agulhas leakage, the transport of water from the Indian to the Atlantic Ocean, is investigated in a high-resolution numerical ocean model. Sudden eastward retreats of the Agulhas Current retroflection loop are linearly related to the shedding of Agulhas rings, where larger retreats generate larger rings. Using numerical Lagrangian floats a 37 year time series of the magnitude of Agulhas leakage in the model is constructed. The time series exhibits large amounts of variability, both on weekly and annual time scales. A linear relation is found between the magnitude of Agulhas leakage and the location of the Agulhas Current retroflection, both binned to three month averages. In the relation, a more westward location of the Agulhas Current retroflection corresponds to an increased transport from the Indian Ocean to the Atlantic Ocean. When this relation is used in a linear regression and applied to almost 20 years of altimetry data, it yields a best estimate of the mean magnitude of Agulhas leakage of 13.2 Sv. The early retroflection of 2000, when Agulhas leakage was probably halved, can be identified using the regression.
    Type of Medium: Online Resource
    Pages: graph. Darst
    ISSN: 1812-0792
    URL: http://www.ocean-sci.net/5/511/2009/os-5-511-2009.pdf
    Language: English
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    GEOMAR CATALOGUE
    Link to Library Catalog
    get availability status
  • 5
    Online Resource
    Online Resource
    Observed and simulated estimates of the meridional overturning circulation at 26.5° N in the Atlantic (2009)
    Details Availability
    In: Ocean science, Katlenburg-Lindau : Copernicus Publ., 2005, 5(2009), 4, Seite 575-589, 1812-0792
    In: volume:5
    In: year:2009
    In: number:4
    In: pages:575-589
    Description / Table of Contents: Daily timeseries of the meridional overturning circulation (MOC) estimated from the UK/US RAPID/MOCHA array at 26.5° N in the Atlantic are used to evaluate the MOC as simulated in two global circulation models: (I) an 8-member ensemble of the coupled climate model ECHAM5/MPI-OM, and (II) the ECCO-GODAE state estimate. In ECHAM5/MPI-OM, we find that the observed and simulated MOC have a similar variability and time-mean within the 99% confidence interval. In ECCO-GODAE, we find that the observed and simulated MOC show a significant correlation within the 99% confidence interval. To investigate the contribution of the different transport components, the MOC is decomposed into Florida Current, Ekman and mid-ocean transports. In both models, the mid-ocean transport is closely approximated by the residual of the MOC minus Florida Current and Ekman transports. As the models conserve volume by definition, future comparisons of the RAPID/MOCHA mid-ocean transport should be done against the residual transport in the models. The similarity in the variance and the correlation between the RAPID/MOCHA, and respectively ECHAM5/MPI-OM and ECCO-GODAE MOC estimates at 26.5° N is encouraging in the context of estimating (natural) variability in climate simulations and its use in climate change signal-to-noise detection analyses. Enhanced confidence in simulated hydrographic and transport variability will require longer observational time series.
    Type of Medium: Online Resource
    Pages: graph. Darst
    ISSN: 1812-0792
    URL: http://www.ocean-sci.net/5/575/2009/os-5-575-2009.html
    Language: English
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    GEOMAR CATALOGUE
    Link to Library Catalog
    get availability status
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...