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| Titel |
Late Holocene diatom-based sea-surface temperature reconstruction from the
Conrad Rise, Southern Ocean |
| VerfasserIn |
Lisa Orme, Arto Mietinnen, Xavier Crosta, Rahul Mohan |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250142754
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| Publikation (Nr.) |
 EGU/EGU2017-6408.pdf |
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| Zusammenfassung |
| The Southern Ocean plays an important role in the global climate system. The temperature
and sea ice extent alter the latitudinal temperature gradient of the Southern Ocean, which can
be transferred to the atmosphere resulting in changes in the southern westerly winds. The
temperature, sea ice and wind variations are also factors influencing Antarctic Bottom Water
formation, which is a control on the strength of the Atlantic Meridional Overturning
Circulation. Therefore conditions in the Southern Ocean may influence the climate in
the northern and southern hemispheres. The Southern Ocean and North Atlantic
were connected during the Last Glacial during Dansgaard-Oeschger events, when
variations in ocean circulation caused a bipolar seesaw of temperatures. For the
Holocene there is less evidence for a bipolar seesaw, although recent research shows
concurrent, opposite trends in ocean circulation in the North Atlantic and in the Southern
Ocean. Further reconstructions are required from the Southern Ocean in particular to
enable greater understanding of how the temperature and sea ice varied during the
Holocene.
The OCTEL project (Ocean-sea-ice-atmosphere teleconnections between the Southern
Ocean and North Atlantic during the Holocene) aims to investigate the ocean, atmosphere
and sea-ice teleconnections for the Holocene using new, high resolution records from both the
Southern Ocean and North Atlantic. We here present initial results from diatom analysis
conducted on a sediment core from the Southern Ocean, sampled from the Conrad Rise
(54˚ 16.04’S, 39˚ 45.98’W). The preliminary results highlight a dominance of
diatom species Fragilariopsis kerguelensis and Thalassiosira lentiginosa, with lower
abundances of Thalassiothrix antarctica and Thalassiosira gracilis among others, which
suggests an open ocean setting close to the polar front. The diatom data will be
converted to quantitative reconstructions of summer sea surface temperature and
sea ice presence using the Modern Analogue Technique. It is hoped that the new
reconstructions in combination with existing records and modelling will enable improved
understanding of the patterns and causes of interhemispheric ocean and climate variability. |
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