Reconstruction of the spatial and temporal variability of the surface to subsurface ocean dynamics of the North West Pacific during the Pliocene and Pleistocene
The North Pacific (NP) is an essential component of the global climate system as it acts as a significant natural carbon sink and neutralizes a part of the anthropogenic release of CO2. The efficiency of the NP carbon sink depends on a range of variable factors, including gyre circulation, the wind...
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| Other Authors: | , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
2023
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| Online Access: | https://nbn-resolving.org/urn:nbn:de:gbv:8:3-2023-00938-7 https://macau.uni-kiel.de/receive/macau_mods_00004275 https://macau.uni-kiel.de/servlets/MCRFileNodeServlet/macau_derivate_00005525/Dissertation_Lara_Jacobi.pdf |
| Summary: | The North Pacific (NP) is an essential component of the global climate system as it acts as a significant natural carbon sink and neutralizes a part of the anthropogenic release of CO2. The efficiency of the NP carbon sink depends on a range of variable factors, including gyre circulation, the wind system, influences from tropical and subpolar regions, and internal reorganizations like stratification changes. Thus, a detailed investigation of the NP ocean-climate system of the past is crucial to understand how the ongoing climate change influences this region and will affect future global climate. This thesis, presents proxy records approximating (sub)-surface temperature (foraminiferal Mg/Ca), salinity (combined Mg/Ca and δ18), biological productivity (XRF based element ratios, CaCO3 content and alkenone concentrations) and terrigenous input via wind (XRF-based Fe) from a unique set of six sediment cores from a meridional transect from Hess Rise to the subarctic NP retrieved during R/V SONNE expeditions 202 and 264. The records reveal significantly different upper ocean conditions and a different productivity pattern in the western NP during the Pliocene than during the Pleistocene. This is associate with the intensification of Northern Hemisphere Glaciation, the onset of a permanent halocline and increased seasonality. Further, a different productivity and carbonate deposition/dissolution pattern of records south of 40°N compared to northern cores is linked to different nutrient regimes of the subtropical and subpolar gyre. Moreover, abrupt and pronounced changes in SST at site SO264-45 (e.g. at 480 ka and 280 ka) indicate shifts of the Subarctic Front induced by changes in the strength of the Kuroshio Extension, e.g., caused by sustained La Niña-like conditions in the tropical Pacific. |
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