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  • 1
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    Stable hydrogen and carbon isotopes of C37 alkenones during Termination I and II
    PANGAEA
    In:  Supplement to: Kasper, Sebastian; van der Meer, Marcel T J; Mets, Anchelique; Zahn, Rainer; Sinninghe Damsté, Jaap S; Schouten, Stefan (2014): Salinity changes in the Agulhas leakage area recorded by stable hydrogen isotopes of C37 alkenones during Termination I and II. Climate of the Past, 10(1), 251-260, https://doi.org/10.5194/cp-10-251-2014
    Details
    Publikationsdatum: 2023-05-12
    Beschreibung: At the southern tip of Africa, the Agulhas Current reflects back into the Indian Ocean causing so-called "Agulhas rings" to spin off and release relatively warm and saline water into the South Atlantic Ocean. Previous reconstructions of the dynamics of the Agulhas Current, based on paleo-sea surface temperature and sea surface salinity proxies, inferred that Agulhas leakage from the Indian Ocean to the South Atlantic was reduced during glacial stages as a consequence of shifted wind fields and a northwards migration of the subtropical front. Subsequently, this might have led to a buildup of warm saline water in the southern Indian Ocean. To investigate this latter hypothesis, we reconstructed sea surface salinity changes using alkenone dD, and paleo-sea surface temperature using TEXH 86 and UK'37, from two sediment cores (MD02-2594, MD96-2080) located in the Agulhas leakage area during Termination I and II. Both UK'37 and TEXH 86 temperature reconstructions indicate an abrupt warming during the glacial terminations, while a shift to more negative dDalkenone values of approximately 14 per mil during glacial Termination I and II is also observed. Approximately half of the isotopic shift can be attributed to the change in global ice volume, while the residual isotopic shift is attributed to changes in salinity, suggesting relatively high salinities at the core sites during glacials, with subsequent freshening during glacial terminations. Approximate estimations suggest that dDalkenone represents a salinity change of ca. 1.7-1.9 during Termination I and Termination II. These estimations are in good agreement with the proposed changes in salinity derived from previously reported combined planktonic Foraminifera d18O values and Mg/Ca-based temperature reconstructions. Our results confirm that the dD of alkenones is a potentially suitable tool to reconstruct salinity changes independent of planktonic Foraminifera d18O.
    Schlagwort(e): NIOZ_UU; NIOZ Royal Netherlands Institute for Sea Research, and Utrecht University
    Materialart: Dataset
    Format: application/zip, 2 datasets
    Standort Signatur Einschränkungen Verfügbarkeit
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    DATA PANGAEA
  • 2
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    (Table 1) Stable hydrogen and carbon isotopes of C37 alkenones during Termination I and II of sediment core MD96-2080 (2014)
    PANGAEA
    Details
    Publikationsdatum: 2023-12-22
    Schlagwort(e): AGE; Alkenone, C37, δ13C; Alkenone, C37, δ13C, standard deviation; Alkenone, unsaturation index UK'37; CALYPSO; Calypso Corer; IMAGES II; Marion Dufresne (1995); MD105; MD96-2080; MD962080, ABS; NIOZ_UU; NIOZ Royal Netherlands Institute for Sea Research, and Utrecht University; Southern Agulhas Bank; Tetraether index of 86 carbon atoms, high-temperature region; δ Deuterium, alkenone, C37; δ Deuterium, alkenone, C37, standard deviation
    Materialart: Dataset
    Format: text/tab-separated-values, 127 data points
    Standort Signatur Einschränkungen Verfügbarkeit
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    DATA PANGAEA
  • 3
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    (Table 2) Stable hydrogen and carbon isotopes of C37 alkenones during Termination I and II of sediment core MD02-2594 (2014)
    PANGAEA
    Details
    Publikationsdatum: 2023-12-22
    Schlagwort(e): AGE; Alkenone, C37, δ13C; Alkenone, C37, δ13C, standard deviation; Alkenone, unsaturation index UK'37; CALYPSO; Calypso Corer; Marion Dufresne (1995); MD02-2594; MD128; NIOZ_UU; NIOZ Royal Netherlands Institute for Sea Research, and Utrecht University; Southern Ocean; SWAF; Tetraether index of 86 carbon atoms, high-temperature region; δ Deuterium, alkenone, C37; δ Deuterium, alkenone, C37, standard deviation
    Materialart: Dataset
    Format: text/tab-separated-values, 80 data points
    Standort Signatur Einschränkungen Verfügbarkeit
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    DATA PANGAEA
  • 4
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    delta Deuterium of alkenone and BIT index of sediment core 64PE304-80 samples (2014)
    PANGAEA
    In:  Supplement to: Kasper, Sebastian; van der Meer, Marcel T J; Castañeda, Isla S; Tjallingii, Rik; Brummer, Geert-Jan A; Sinninghe Damsté, Jaap S; Schouten, Stefan (2015): Testing alkenone D/H ratio as a paleo indicator of sea surface salinity in a coastal ocean margin (Mozambique Channel). Organic Geochemistry, 78, 62-68, https://doi.org/10.1016/j.orggeochem.2014.10.011
    Details
    Publikationsdatum: 2023-12-22
    Beschreibung: Reconstructing past ocean salinity is important for assessing paleoceanographic change and therefore past climatic dynamics. Commonly, sea water salinity reconstruction is based on foraminifera oxygen isotope ratio values combined with sea surface temperature reconstruction. However, the approach relies on multiple proxies, resulting in relatively large uncertainty and, consequently, relatively low accuracy of salinity estimates. An alternative tool for past ocean salinity reconstruction is the hydrogen isotope composition of long chain (C37) alkenones (dDalkenone). Here, we applied dDalkenone to a 39 ka long coastal sediment record from the Eastern South African continental shelf in the Mozambique Channel, close to the Zambezi River mouth. Despite changes in global sea water dD related to glacial - interglacial ice volume effects, no clear changes were observed in the dDalkenone record throughout the entire 39 ka. The BIT index record from the same core showed high BIT values during the glacial and low values during the Holocene. This indicates a more pronounced freshwater influence at the core location during the glacial, resulting in alkenones depleted in deuterium during that time and, thereby, explains the lack of a clear glacial-interglacial alkenone dD shift. Correlation between the BIT index and dDalkenone during the glacial period suggests that increased continental runoff potentially changed the growth conditions of the alkenone producing haptophytes, promoting coastal haptophyte species with generally more enriched dDalkenone values. We therefore suggest that the application of dDalkenone for reconstructing past salinity in coastal settings may be complicated by changes in the alkenone producing haptophyte community.
    Schlagwort(e): 64PE304; 64PE304-80; AGE; Alkenone C37/C38 ratio; Branched and isoprenoid tetraether index; DEPTH, sediment/rock; GC; Gravity corer; INATEX-GEO; Pelagia; South-East African margin; δ Deuterium, alkenone; δ Deuterium, alkenone, standard deviation
    Materialart: Dataset
    Format: text/tab-separated-values, 591 data points
    Standort Signatur Einschränkungen Verfügbarkeit
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    DATA PANGAEA
  • 5
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    Comment on “A snapshot of climate variability at Tahiti at 9.5 ka using a fossil coral from IODP Expedition 310” by Kristine L. DeLong, Terrence M. Quinn, Chuan-Chou Shen, and Ke Lin (2011)
    AGU (American Geophysical Union)
    In:  Geochemistry, Geophysics, Geosystems, 12 (3). Q03012.
    Details
    Publikationsdatum: 2019-09-23
    Beschreibung: [1] The Integrated Ocean Drilling Program (IODP) Expedition 310 recovered drill cores from the drowned reefs around the island of Tahiti (17°40′S, 149°30′W), many of which contained samples of massive corals from the genus Porites. Herein we report on one well-preserved fossil coral sample: a 13.6 cm long Porites sp. dated by uranium series techniques at 9523 ± 33 years. Monthly δ18O and Sr/Ca determinations reveal nine clear and robust annual cycles. Coral δ18O and Sr/Ca determinations estimate a mean temperature of ∼24.3°C (∼3.2°C colder than modern) for Tahiti at 9.5 ka; however, this estimate is viewed with caution since potential sources of cold bias in coral geochemistry remain to be resolved. The interannual variability in coral δ18O is similar between the 9.5 ka coral record and a modern record from nearby Moorea. The seasonal cycle in coral Sr/Ca is approximately the same or greater in the 9.5 ka coral record than in modern coral records from Tahiti. Paired analysis of coral δ18O and Sr/Ca indicates cold/wet (warm/dry) interannual anomalies, opposite from those observed in the modern instrumental record.
    Materialart: Article , PeerReviewed
    Format: text
    DOI: 10.1029/2010GC003377
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
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    Experimental characterization of a quantum many-body system via higher-order correlations (2017)
    Nature Publishing Group (NPG)
    In: Nature
    Details
    Publikationsdatum: 2017-05-18
    Beschreibung: Experimental characterization of a quantum many-body system via higher-order correlations Nature 545, 7654 (2017). doi:10.1038/nature22310 Authors: Thomas Schweigler, Valentin Kasper, Sebastian Erne, Igor Mazets, Bernhard Rauer, Federica Cataldini, Tim Langen, Thomas Gasenzer, Jürgen Berges & Jörg Schmiedmayer Quantum systems can be characterized by their correlations. Higher-order (larger than second order) correlations, and the ways in which they can be decomposed into correlations of lower order, provide important information about the system, its structure, its interactions and its complexity. The measurement of such correlation functions is therefore an essential tool for reading, verifying and characterizing quantum simulations. Although higher-order correlation functions are frequently used in theoretical calculations, so far mainly correlations up to second order have been studied experimentally. Here we study a pair of tunnel-coupled one-dimensional atomic superfluids and characterize the corresponding quantum many-body problem by measuring correlation functions. We extract phase correlation functions up to tenth order from interference patterns and analyse whether, and under what conditions, these functions factorize into correlations of lower order. This analysis characterizes the essential features of our system, the relevant quasiparticles, their interactions and topologically distinct vacua. From our data we conclude that in thermal equilibrium our system can be seen as a quantum simulator of the sine-Gordon model, relevant for diverse disciplines ranging from particle physics to condensed matter. The measurement and evaluation of higher-order correlation functions can easily be generalized to other systems and to study correlations of any other observable such as density, spin and magnetization. It therefore represents a general method for analysing quantum many-body systems from experimental data.
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von Nature Publishing Group (NPG)
    Standort Signatur Einschränkungen Verfügbarkeit
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    PAPER CURRENT
  • 7
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    Experimental characterization of a quantum many-body system via higher-order correlations (2017)
    Nature Publishing Group (NPG)
    In: Nature
    Details
    Publikationsdatum: 2017-05-19
    Beschreibung: Experimental characterization of a quantum many-body system via higher-order correlations Nature 545, 7654 (2017). doi:10.1038/nature22310 Authors: Thomas Schweigler, Valentin Kasper, Sebastian Erne, Igor Mazets, Bernhard Rauer, Federica Cataldini, Tim Langen, Thomas Gasenzer, Jürgen Berges & Jörg Schmiedmayer Quantum systems can be characterized by their correlations. Higher-order (larger than second order) correlations, and the ways in which they can be decomposed into correlations of lower order, provide important information about the system, its structure, its interactions and its complexity. The measurement of such correlation functions is therefore an essential tool for reading, verifying and characterizing quantum simulations. Although higher-order correlation functions are frequently used in theoretical calculations, so far mainly correlations up to second order have been studied experimentally. Here we study a pair of tunnel-coupled one-dimensional atomic superfluids and characterize the corresponding quantum many-body problem by measuring correlation functions. We extract phase correlation functions up to tenth order from interference patterns and analyse whether, and under what conditions, these functions factorize into correlations of lower order. This analysis characterizes the essential features of our system, the relevant quasiparticles, their interactions and topologically distinct vacua. From our data we conclude that in thermal equilibrium our system can be seen as a quantum simulator of the sine-Gordon model, relevant for diverse disciplines ranging from particle physics to condensed matter. The measurement and evaluation of higher-order correlation functions can easily be generalized to other systems and to study correlations of any other observable such as density, spin and magnetization. It therefore represents a general method for analysing quantum many-body systems from experimental data.
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von Nature Publishing Group (NPG)
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    PAPER CURRENT
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