Reconstruction of surface water stratification changes in the northwestern Pacific of the last 180 kyrs
| Autor: | Wan-Jung Tsai, 蔡宛蓉 |
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| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 104 The North Pacific Intermediate Water (NPIW) plays an important role on driving the global climate change, which can control the heat transportation from low to high latitude. However, the long-term changes of NPIW are still rare understood. In this study, by using Unsaturated Alkenone Index (U_37^(k^'' )) and foraminiferal Mg/Ca to represent the different temperature of water depths, the historical hydrography evolution of water profile can be reconstructed. Therefore, we can investigate the relationship between climate events and the circulation changes in northwestern Pacific.As the result, using ΔT to reconstruct the mixed layer change is applicable in Shatsky Rise, and we suggest to use other species which have small estimating errors, in order to get more reliability results on western Pacific paleoceanographic studies. The U_37^(k^'' ) temperatures reveal a regional cold period during MIS 5e in Shatsky Rise, which is probably not caused by the movement of Subarctic Front, but the violently fluctuation of the Kuroshio Extension. The result ofΔTU-N and ΔTU-G show thatΔTU-G are more sensitive than ΔTU-N, in which that ΔTU-N is more truly represent the change of NPIW. Reconstructed ΔTU-N and ΔTU-G curves indicate that MIS 2 is warmer than MIS6. Otherwise, ventilation age data confirmed that the mixed layer is deeper during the late MIS 3. In MIS 5, both ΔTU-N and ΔTU-G records illustrate the increased mixed layer depth during warm periods, but decreased in cold periods. Therefore, the stratification is weakened which the circulation of NPIW can be strengthen during the cold periods. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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