GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • 2020-2022  (9)
Publikationsart
Schlagwörter
Verlag/Herausgeber
Erscheinungszeitraum
Jahr
  • 1
    facet.materialart.
    Unbekannt
    Antarctic Circumpolar Current Dynamics at the Pacific Entrance to the Drake Passage Over the Past 1.3 Million Years (2020)
    American Geophysical Union
    In:  EPIC3Paleoceanography and Paleoclimatology, American Geophysical Union, 35(7), pp. e2019PA003773, ISSN: 2572-4525
    Details
    Publikationsdatum: 2021-02-01
    Beschreibung: The Antarctic Circumpolar Current (ACC) is the world's largest current system connecting all three major basins of the global ocean. Our knowledge of glacial‐interglacial changes in ACC dynamics in the southeast Pacific is not well constrained and presently only based on reconstructions covering the last glacial cycle. Here we use a combination of mean sortable silt grain size of the terrigenous sediment fraction (10–63 μm, "Sortable Silt") and X‐ray fluorescence scanner‐derived Zr/Rb ratios as flow strength proxies to examine ACC variations at the Pacific entrance to the Drake Passage (DP) in the vicinity of the Subantarctic Front. Our results indicate that at the DP entrance, ACC strength varied by ~6–16% on glacial‐interglacial time scales, yielding higher current speeds during interglacial times and reduced current speeds during glacials. We provide evidence that previous observations of a reduction in DP throughflow during the last glacial period are part of a consistent pattern extending for at least the last 1.3 Ma. The orbital‐scale cyclicity follows well‐known global climate changes from prevailing ca. 41‐kyr cycles in the early part of the record (1.3 Ma to 850 ka; marine isotope stage 21) across the mid‐Pleistocene transition into the middle and late Pleistocene 100‐kyr world. A comparison to a bottom water flow record from the deep western boundary current off New Zealand (Ocean Drilling Program Site 1123) reveals anti‐phased changes between the two sites. The enhanced supply of deep water along the DP and into the Atlantic Ocean during interglacials corresponds to a weakened flow of the SW Pacific deep western boundary current.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 2
    facet.materialart.
    Unbekannt
    Sea ice dynamics in the Bransfield Strait, Antarctic Peninsula, during the past 240 years: a multi-proxy intercomparison study (2020)
    Copernicus
    In:  EPIC3Climate of the Past, Copernicus, 16(6), pp. 2459-2483, ISSN: 1814-9332
    Details
    Publikationsdatum: 2021-06-16
    Beschreibung: In the last decades, changing climate conditions have had a severe impact on sea ice at the western Antarctic Peninsula (WAP), an area rapidly transforming under global warming. To study the development of spring sea ice and environmental conditions in the pre-satellite era we investigated three short marine sediment cores for their biomarker inventory with a particular focus on the sea ice proxy IPSO25 and micropaleontological proxies. The core sites are located in the Bransfield Strait in shelf to deep basin areas characterized by a complex oceanographic frontal system, coastal influence and sensitivity to large-scale atmospheric circulation patterns. We analyzed geochemical bulk parameters, biomarkers (highly branched isoprenoids, glycerol dialkyl glycerol tetraethers, sterols), and diatom abundances and diversity over the past 240 years and compared them to observational data, sedimentary and ice core climate archives, and results from numerical models. Based on biomarker results we identified four different environmental units characterized by (A) low sea ice cover and high ocean temperatures, (B) moderate sea ice cover with decreasing ocean temperatures, (C) high but variable sea ice cover during intervals of lower ocean temperatures, and (D) extended sea ice cover coincident with a rapid ocean warming. While IPSO25 concentrations correspond quite well to satellite sea ice observations for the past 40 years, we note discrepancies between the biomarker-based sea ice estimates, the long-term model output for the past 240 years, ice core records, and reconstructed atmospheric circulation patterns such as the El Niño–Southern Oscillation (ENSO) and Southern Annular Mode (SAM). We propose that the sea ice biomarker proxies IPSO25 and PIPSO25 are not linearly related to sea ice cover, and, additionally, each core site reflects specific local environmental conditions. High IPSO25 and PIPSO25 values may not be directly interpreted as referring to high spring sea ice cover because variable sea ice conditions and enhanced nutrient supply may affect the production of both the sea-ice-associated and phytoplankton-derived (open marine, pelagic) biomarker lipids. For future interpretations we recommend carefully considering individual biomarker records to distinguish between cold sea-ice-favoring and warm sea-ice-diminishing environmental conditions.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 3
    facet.materialart.
    Unbekannt
    Southern California's megaflood event of ca. 1605 AD linked to large-scale atmospheric forcing (2021)
    In:  http://aquaticcommons.org/id/eprint/14822 | 8 | 2014-12-10 22:52:53 | 14822
    Details
    Publikationsdatum: 2021-06-25
    Beschreibung: A distinct, 1- to 2-cm-thick flood deposit found in Santa Barbara Basin with a varve-date of 1605 AD ± 5 years testifies to an intensity of precipitation that remains unmatched for later periods when historical or instrumental records can be compared against the varve record. The 1605 AD ± 5 event correlates well with Enzel's (1992) finding of a Silver Lake playa perennial lake at the terminus of the Mojave River (carbon-14-dated 1560 AD ± 90 years), in relative proximity to the rainfall catchment area draining into Santa Barbara Basin. According to Enzel, such a persistent flooding of the Silver Lake playa occurred only once during the last 3,500 years and required a sequence of floods, each comparable in magnitude to the largest floods in the modern record. To gain confidence in dating of the 1605 AD ± 5 event, we compare Southern California's sedimentary evidence against historical reports and multi-proxy time-series that indicate unusual climatic events or are sensitive to changes in large-scale atmospheric circulation patterns. The emerging pattern supports previous suggestions that the first decade of the 17th century was marked by a rapid cooling of the Northern Hemisphere, with some indications for global coverage. A burst of volcanism and the occurrence of El Nino seem to have contributed to the severity of the events. The synopsis of the 1605 AD ± 5 years flood deposit in Santa Barbara Basin, the substantial freshwater body at Silver Lake playa, and much additional paleoclimatic, global evidence testifiesfor an equatorward shift of global wind patterns as the world experienced an interval of rapid, intense, and widespread cooling.
    Schlagwort(e): Atmospheric Sciences ; Earth Sciences ; Limnology ; Oceanography ; PACLIM ; dendrochronology
    Repository-Name: AquaDocs
    Materialart: conference_item
    Format: application/pdf
    Format: application/pdf
    Format: 39-62
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 4
    facet.materialart.
    Unbekannt
    Climatic changes reflected in laminated Santa Barbara Basin sediments (2021)
    In:  http://aquaticcommons.org/id/eprint/15571 | 8 | 2014-11-06 00:53:53 | 15571
    Details
    Publikationsdatum: 2021-07-08
    Beschreibung: Dating of annually varved sediments of Santa Barbara Basin down to AD 1650 in absence of precise radiometric methods was achieved by (1) counting varves and determining mean annual sedimentation rates from x-radiographs, and (2) correlation with historical rainfall and tree-ring records.
    Schlagwort(e): Atmospheric Sciences ; Earth Sciences ; Oceanography ; PACLIM ; dendrochronology
    Repository-Name: AquaDocs
    Materialart: conference_item
    Format: application/pdf
    Format: application/pdf
    Format: 97-99
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 5
    facet.materialart.
    Unbekannt
    Seasonal resolution of laminated sediments in Santa Barbara Basin: its significance in paleoclimatic studies (2021)
    In:  http://aquaticcommons.org/id/eprint/15677 | 8 | 2014-11-19 19:33:45 | 15677
    Details
    Publikationsdatum: 2021-07-09
    Beschreibung: Sediments in Santa Barbara Basin contain microfossil and sedimentological information that allows reconstruction of major features of the California Current such as water temperature, strength of upwelling, and productivity. ... Until now, investigations of Santa Barbara Basin sediments have utilized analytical techniques that could not resolve seasonal laminae, permitting annual resolution of variations in sediment composition and structure only. ... Based on a successful technique for preparation of epoxy-embedded and highly polished thin-sections that permit economical optical and electron microscope evaluation of laminated sequences, it is our long-term goal to reconstruct, with unprecedented detail, the history of sedimentation processes in the Santa Barbara Basin by developing ultra-high-resolution time series of biotic and detrital proxies.
    Schlagwort(e): Earth Sciences ; Oceanography ; PACLIM
    Repository-Name: AquaDocs
    Materialart: conference_item
    Format: application/pdf
    Format: application/pdf
    Format: 83-92
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 6
    facet.materialart.
    Unbekannt
    The near-AD 1600 multi-proxy puzzle (2021)
    In:  http://aquaticcommons.org/id/eprint/15836 | 8 | 2014-12-12 00:48:34 | 15836
    Details
    Publikationsdatum: 2021-07-10
    Beschreibung: EXTRACT (SEE PDF FOR FULL ABSTRACT):A varve chronology with annual resolution (AD 1117-1992) has been developed recently for Santa Barbara Basin. Varve thickness and water content show an exponential trend consistent with expected patterns in the presence of sediment compaction over time. Annual varve thickness was decomposed into orthogonal components using singular spectrum analysis (SSA) to identify and retrieve inter-decadal oscillations. ... This suggests a connection with global-scale decadal cycles identified in the subtropical Pacific gyre circulation and, possibly, with solar-driven phenomena. The near-1600 AD event coincides with (a) a similarly sudden change of state in nearby Santa Monica Basin that triggered the onset of anoxic conditions and the preservation of laminated sediments, (b) an extreme drought over the American Southwest, (c) a transformation of the age structure in a number of forest populations throughout Arizona and New Mexico. Total organic carbon burial flux in Santa Barbara Basin varves also shows a marked change after AD 1600. A possible climatic link is proposed that involves pathways for moisture transport in the Southwest at decadal and longer time scales.
    Schlagwort(e): Atmospheric Sciences ; Earth Sciences ; Environment ; Oceanography ; PACLIM
    Repository-Name: AquaDocs
    Materialart: conference_item
    Format: application/pdf
    Format: application/pdf
    Format: 169-191
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 7
    facet.materialart.
    Unbekannt
    Integrating varve and tree-ring time series for southern California climate reconstruction: a 20th century outlook [abstract] (2021)
    In:  http://aquaticcommons.org/id/eprint/15810 | 8 | 2014-12-08 23:54:13 | 15810
    Details
    Publikationsdatum: 2021-07-10
    Beschreibung: EXTRACT (SEE PDF FOR FULL ABSTRACT):Our objective is to combine terrestrial and oceanic records for reconstructing West Coast climate. Tree rings and marine laminated sediments provide high-resolution, accurately dated proxy data on the variability of climate and on the productivity of the ocean and have been used to reconstruct precipitation, temperature, sea level pressure, primary productivity, and other large-scale parameters. We present here the latest Santa Barbara basin varve chronology for the twentieth century as well as a newly developed tree-ring chronology for Torrey pine.
    Schlagwort(e): Atmospheric Sciences ; Earth Sciences ; Oceanography ; PACLIM ; dendrochronology
    Repository-Name: AquaDocs
    Materialart: conference_item
    Format: application/pdf
    Format: application/pdf
    Format: 205-205
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 8
    facet.materialart.
    Unbekannt
    Environmental and coastline changes controlling Holocene carbon accumulation rates in fjords of the western Strait of Magellan region (2020)
    In:  EPIC3Continental Shelf Research, 199, pp. 104101, ISSN: 02784343
    Details
    Publikationsdatum: 2020-05-18
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 9
    facet.materialart.
    Unbekannt
    Multiproxy climate and sea ice reconstruction of the industrial era at the Western Antarctic Peninsula Introduction and study area (2020)
    In:  EPIC3EGU General Assembly 2020, 2020-05-04-2020-05-08Multiproxy climate and sea ice reconstruction of the industrial era at the Western Antarctic Peninsula
    Details
    Publikationsdatum: 2020-06-02
    Beschreibung: This is our presentation at the EGU 2020 (condensed to the highlights of the study) Abstract: Recent changes and variability in climate conditions leave a significant footprint on the distribution and properties of sea ice, as it is sensitive to environmental variations. We investigate the rapidly transforming region of the Western Antarctic Peninsula (WAP) focusing on the conditions and development of sea ice in the pre-satellite era. For this study on past sea ice cover we apply the novel proxy IPSO25 (Ice Proxy for the Southern Ocean with 25 carbon atoms; Belt et al., 2016). Three sampling sites were selected to cover areas near the Antarctic mainland, in the Bransfield Basin (2000 m depth) and the deeper shelf under an oceanographic frontal system. Analysis of short cores (multicores) resolving the last 200 years (based on 210Pbex dating) focused on geochemical bulk parameters, biomarkers (highly branched isoprenoids, GDGTs, sterols) and diatoms. These results are compared to multiple climate archives and modelled data. This multiproxy based approach provides insights on changes in spring sea ice cover, primary production regimes, subsurface ocean temperature (SOT based on TEXL86) and oceanographic as well as atmospheric circulation patterns. While environmental proxies preserved in two cores near the coast and in the Bransfield Basin reflect the properties of water masses from the Bellingshausen Sea and Weddell Sea, respectively, data from the third core at the deeper shelf depict mixed signals of both water masses. Our study reveals clear evidence for warm and cold periods matching with ice core records and other marine sediment data at the WAP. We observe a general decrease in SOT and an increase in sea ice cover overprinted by high decadal fluctuations. Trends in SOT seem to be decoupled from atmospheric temperatures in the 20th century, and this is supported by previous studies (e.g. Barbara et al., 2013), and may be related to the Southern Annual Mode. We consider numerical modelling of sea ice conditions, sea surface temperature and SOT for further support of our findings.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Conference , notRev
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...