Late Quaternary paleoceanographic history of the Pacific sector of the Southern Ocean based on diatom evidence

• Main Author: Benz, Verena
• Format: Thesis
• Language: unknown
• Published: http://www.suub.uni-bremen.de 2016
• Subjects: Antarc*; Antarctic; Sea ice; Southern Ocean
• Online Access: https://epic.awi.de/id/eprint/42877/; https://epic.awi.de/id/eprint/42877/1/PHD_Benz_2016.pdf; https://hdl.handle.net/10013/epic.49441; https://hdl.handle.net/10013/epic.49441.d001

The last transition from a full glacial to a full interglacial state is of special importance to investigate processes that control the Earth’s climate evolution. Out of phase interhemispheric climate variability over the last deglaciation has been associated with orbital induced insolation changes as well as with the “bipolar seesaw”, hence related to changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC). The Southern Ocean (SO) as only water territory connecting the Pacific, Atlantic and Indian Ocean, plays a crucial role as southern limb of the AMOC in propagating signals within its basins and into the different world oceans. The Antarctic Circumpolar Current (ACC), steered by the strong Southern Westerly Winds (SWW), redistributes heat, salt and nutrients via wind-driven upwelling and thus has the high potential of regulating atmospheric CO2 concentration via the biological pump as well as surface and deep-water ventilation. Sea surface temperature and sea-ice extent are important surface water parameters related to the oceanic frontal and current systems as well as to water mass formation via brine release and bioproductivity changes. Despite numerous marine studies from the Pacific sector of the SO, the (sub)antarctic realm is still underrepresented in paleoceanographic research. This thesis examines the environmental changes of the last 30,000 years (30 kyr) in the Pacific sector of the SO using diatom-based transfer function estimates of summer sea surface temperature (SSST) and winter sea-ice (WSI) concentrations reconstructed from 17 selected sediment cores. Including available sea surface temperatures and sea-ice records from the Pacific sector the thesis objectives are primarily a basin and circum-Antarctic wide comprehension of last glacial, deglacial and Holocene climate variability with respect to forcing mechanisms, lead-lag conditions and ice-ocean-atmosphere-ocean feedbacks. The first manuscript deals with the reconstruction of temperature and sea-ice signals during ...