Simulation of Kuroshio during Last Glacial Maximum

• Main Authors: Chia-En Chuang, 莊嘉恩
• Other Authors: Yuan-Pin Chang
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/p2mkmv

碩士 === 國立中山大學 === 海洋科學系研究所 === 106 === The Kuroshio transports heat and energy from tropical region to higher latitude area. The history of Kuroshio variation can be reconstructed by sediment core record and numerical model simulation. The Kuroshio during Last Glacial Maximum (LGM) has been suggested to be mainly controlled by bathymetry, wind field and solar radiations. Firstly, the present Kuroshio is reconstructed by the Kuroshio Current Model, which is built up based on the Princeton Ocean Model (POM), with the present bottom topography and atmospheric forcing. Further, the LGM Kuroshio is simulated by forcing the Kuroshio Current Model with the LGM bathymetry (subtracting 135 meters from the present water depth) and wind field (setting as outputs from Paleoclimate Modelling Intercomparison Project, PMIP). By comparing the present and LGM Kuroshio simulations, the main factors leading to the variability of Kuroshio in the LGM are clarified. Supported by the proxy preserved in palaeoceanographic records and our numerical simulations, we found that the Kuroshio main stream during LGM did not enter the Okinawa Trough through the East Taiwan Channel. Instead, it flowed along the eastern side of Ryukyu Islands, where the present Ryukyu Current passes. Our simulations also show that the stronger winter monsoon during LGM transported a considerable amount of surface Kuroshio water into the northern Okinawa Trough through channels among Ryukyu Islands, in agreement with the LGM temperature and salinity recorded in the cores in northern Okinawa Trough. Besides, the impact of large-scale (or basin-scale) and regional winds on the variability of paleo-Kuroshio is also discussed. Thus, we suggested a new pathway of paleo-Kuroshio during Last Glacial Maximum: turning eastward before passing through East Taiwan Channel. In the way going norward, part of transport flowing into northern Okinawa Trough from Ryukyu Trench side through channels between Ryukyu islands due to Ekman transport by strong northeasterly monsoon. Paleo-Kuroshio could play the same role and remained similar velocity structure as the present Kuroshio but flowing along the pathway of present Ryukyu Current during Last Glacial Maximum.