ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

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
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 174 data points
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    facet.materialart.
    Unknown
    PANGAEA
    In:  Supplement to: Rosenthal, Yair; Lear, Caroline H; Oppo, Delia W; Linsley, Braddock K (2006): Temperature and carbonate ion effects on Mg/Ca and Sr/Ca ratios in benthic foraminifera: Aragonitic species Hoeglundina elegans. Paleoceanography, 21(1), PA1007, https://doi.org/10.1029/2005PA001158
    Publication Date: 2020-01-17
    Description: Core top samples from Atlantic (Little Bahama Banks (LBB)) and Pacific (Hawaii and Indonesia) depth transects have been analyzed in order to assess the influence of bottom water temperature (BWT) and aragonite saturation levels on Mg/Ca and Sr/Ca ratios in the aragonitic benthic foraminifer Hoeglundina elegans. Both the Mg/Ca and Sr/Ca ratios in H. elegans tests show a general decrease with increasing water depth. Although at each site the decreasing trends are consistent with the in situ temperature profile, Mg/Ca and Sr/Ca ratios in LBB are substantially higher than in Indonesia and Hawaii at comparable water depths with a greater difference observed with increasing water depth. Because we find no significant difference between results obtained on "live" and "dead" specimens, we propose that these differences are due to primary effects on the metal uptake during test formation. Evaluation of the water column properties at each site suggests that in situ CO3 ion concentrations play an important role in determining the H. elegans Mg/Ca and Sr/Ca ratios. The CO3 ion effect is limited, however, only to aragonite saturation levels ([DeltaCO3]aragonite) below 15 µmol/kg. Above this level, temperature exerts a dominant effect. Accordingly, we propose that Mg/Ca and Sr/Ca in H. elegans tests can be used to reconstruct thermocline temperatures only in waters oversaturated with respect to the mineral aragonite using the following relationships: Mg/Ca = (0.034 ± 0.002)BWT + (0.96 ± 0.03) and Sr/Ca = (0.060 ± 0.002)BWT + (1.53 ± 0.03) (for [DeltaCO3]aragonite 〉 15 µmol/kg). The standard error associated with these equations is about ±1.1°C. Reconstruction of deeper water temperatures is complicated because in undersaturated waters, changes in Mg/Ca and Sr/Ca ratios reflect a combination of changes in [CO3] and BWT. Overall, we find that Sr/Ca, rather than Mg/Ca, in H. elegans may be a more accurate proxy for reconstructing paleotemperatures.
    Type: Dataset
    Format: application/zip, 3 datasets
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    facet.materialart.
    Unknown
    PANGAEA
    In:  Supplement to: Dahl, Kristina A; Oppo, Delia W (2006): Sea surface temperature pattern reconstructions in the Arabian Sea. Paleoceanography, 21(1), PA1014, https://doi.org/10.1029/2005PA001162
    Publication Date: 2020-01-17
    Description: Sea surface temperature (SST) and seawater d18O (d18Ow) were reconstructed in a suite of sediment cores from throughout the Arabian Sea for four distinct time intervals (0 ka, 8 ka, 15 ka, and 20 ka) with the aim of understanding the history of the Indian Monsoon and the climate of the Arabian Sea region. This was accomplished through the use of paired Mg/Ca and d18O measurements of the planktonic foraminifer Globigerinoides ruber. By analyzing basin-wide changes and changes in cross-basinal gradients, we assess both monsoonal and regional-scale climate changes. SST was colder than present for the majority of sites within all three paleotime slices. Furthermore, both the Indian Monsoon and the regional Arabian Sea mean climate have varied substantially over the past 20 kyr. The 20 ka and 15 ka time slices exhibit average negative temperature anomalies of 2.5°-3.5°C attributable, in part, to the influences of glacial atmospheric CO2 concentrations and large continental ice sheets. The elimination of the cross-basinal SST gradient during these two time slices likely reflects a decrease in summer monsoon and an increase in winter monsoon strength. Changes in d18Ow that are smaller than the d18O signal due to global ice volume reflect decreased evaporation and increased winter monsoon mixing. SSTs throughout the Arabian Sea were still cooler than present by an average of 1.4°C in the 8 ka time slice. These cool SSTs, along with lower d18Ow throughout the basin, are attributed to stronger than modern summer and winter monsoons and increased runoff and precipitation. The results of this study underscore the importance of taking a spatial approach to the reconstruction of processes such as monsoon upwelling.
    Type: Dataset
    Format: application/zip, 3 datasets
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 36 data points
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 552 data points
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 443 data points
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    facet.materialart.
    Unknown
    PANGAEA
    In:  Supplement to: Praetorius, Summer K; McManus, Jerry F; Oppo, Delia W; Curry, William B (2008): Episodic reductions in bottom-water currents since the last ice age. Nature Geoscience, 1, 449-452, https://doi.org/10.1038/ngeo227
    Publication Date: 2020-01-18
    Description: Past changes in the freshwater balance of the surface North Atlantic Ocean are thought to have influenced the rate of deep-water formation, and consequently climate (Broecker and Denton, 1989, doi:10.1016/0016-7037(89)90123-3; Manabe and Stouffer, 1996; doi:10.1038/378165a0). Although water-mass proxies are generally consistent with an impact of freshwater input on meridional overturning circulation (Boyle and Keigwin, 1987, doi:10.1038/330035a0), there has been little dynamic evidence to support this linkage. Here we present a 25,000 year record of variations in sediment grain size from south of Iceland, which indicates vigorous bottom-water currents during both the last glacial maximum and the Holocene period. Together with reconstructions of North Atlantic water-mass distribution, vigorous bottom currents suggest a shorter residence time of northern-source waters during the last glacial maximum, relative to the Holocene period. The most significant reductions in flow strength occur during periods that have been associated with freshening of the surface North Atlantic. The short-term deglacial oscillations in bottom current strength are closely coupled to changes in Greenland air temperature, with a minimum during the Younger Dryas cold reversal and a maximum at the time of rapid warming at the onset of the Holocene. Our results support a strong connection between ocean circulation and rapid climate change.
    Type: Dataset
    Format: application/zip, 2 datasets
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 2020-01-18
    Type: Dataset
    Format: text/tab-separated-values, 72 data points
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2020-01-18
    Type: Dataset
    Format: text/tab-separated-values, 298 data points
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    facet.materialart.
    Unknown
    PANGAEA
    In:  Supplement to: Oppo, Delia W; Sun, Youbin (2005): Amplitude and timing of sea-surface temperature change in the northern South China Sea: Dynamic link to the East Asian monsoon. Geology, 33(10), 785-788, https://doi.org/10.1130/G21867.1
    Publication Date: 2020-01-18
    Description: Magnesium/calcium (Mg/Ca) ratios of foraminiferal shells from a sediment core from the northern South China Sea, a semi-enclosed basin in the western tropical Pacific, document variations in sea-surface temperature (SST) during the past 145 k.y. Glacial SSTs were 4°C colder than interglacial SSTs. During the last deglaciation, most of the warming was accomplished in a single abrupt step after continental ice-sheet decay had already begun, but warming and ice-sheet demise were nearly synchronous during the penultimate deglaciation. Abrupt SST changes of the past 15 k.y. were apparently synchronous with events in East Asian monsoon rainfall, suggesting that variations in monsoon winds and their influence on surface circulation of the western Pacific exerted a strong control on northern South China Sea SSTs. We suggest that this link persisted for the previous 130 k.y., during which time orbital-scale 2-3°C SST changes and several small (〈/=2°C) abrupt SST events occurred in the northern South China Sea. The similar timing of northern South China Sea SST, on a benthic d18O time scale, to a well-dated speleothem record from eastern China suggests that the demise of ice sheets associated with the penultimate deglaciation did not precede Northern Hemisphere summer insolation increase. Our results suggest that surface waters had higher d18O values during times of strong summer monsoon than during times of weak monsoon, likely reflecting a redistribution of 18O-depleted rainfall from land during times of strong summer monsoons, to the western Pacific during times of weaker summer monsoons.
    Type: Dataset
    Format: application/zip, 3 datasets
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...