Reconstruction of oceanographic properties and atmospheric circulation at the marginal regions of the Western Pacific Warm Pool during the late Quaternary

• Main Author: 서인아
• Other Authors: 이용일, Seo, Inah, 자연과학대학 지구환경과학부
• Format: Thesis
• Language: English
• Published: 서울대학교 대학원 2016
• Subjects: paleoceanography; late Pleistocene; inter-tropical convergence zone; equatorial Pacific; climate change; 550; Pacific; Ice Sheet
• Online Access: https://hdl.handle.net/10371/121224

학위논문 (박사)-- 서울대학교 대학원 : 지구환경과학부, 2016. 2. 이용일. Evolution of surface ocean environment in the eastern margin of the Western Pacific Warm Pool and its forcing mechanisms during the late Quaternary were investigated using various biogenic and lithogenic components in the northwestern and central equatorial Pacific where paleoclimatic records are rare due to paucity of sedimentary archives. To better understand the coupled behavior and interactions between the atmosphere and surface ocean dynamics, the provenance of eolian mineral dust and the composition of biogenic microfossils were investigated together. For the last 600 kyr, eolian mineral dust deposited in the northwest Pacific, represented by a sediment core (12°30N, 135°00E) from the Philippine Sea, has been supplied predominantly from the central Asian deserts (e.g., Taklimakan desert). It highlights that the prevailing wind system, rather than seasonal monsoon, has been the main transporting agent of eolian dust from Asian inland to the North Pacific. In contrast, eolian mineral dust deposited in a central equatorial Pacific site (5°53N, 177°26W) reveals Australian/South American dust affinity before 0.8 Ma but gradually increasing Asian dust signal after 0.8 Ma. The change in dust provenance was accompanied by an increased dust flux and a decrease in surface productivity and salinity. These changes can be explained by the southward movement of the Intertropical Convergence Zone (ITCZ) and North Equatorial Counter Current (NECC) and the direct influence of these features on the site after 0.8 Ma. The southward movement of the ITCZ is in phase with the warming trend observed in upwelling regions of the equatorial Pacific and Atlantic between 0.9 and 0.8 Ma. The southward movement of the ITCZ from 0.9 to 0.8 Ma indicates more significant cooling in the Northern Hemisphere (NH) than in the Southern Hemisphere across the Mid-Pleistocene Transition, which is supportive of the interpretation that the NH ice sheet expanded significantly and stabilized after 0.9 ...