講演者：台湾大学 Chuan-Chou Shen (沈 川洲) 教授
Title: Orbital-scale East Asian-Australian summer monsoon dynamics and a centennial earth magnetic reversal event at 98 ka
Abstract: Previous studies of stalagmite-inferred East Asian summer monsoon (EASM) records over the past 100s kyr suggest that orbital-scale EASM intensity was predominately driven by precessional forcing of ~20 kyr. In the past years, we reconstructed a tropical precipitation record from the western Pacific since 282 ka, inferred from planktonic foraminiferal rare earth element contents of a marine sediment core collected off the eastern coast of Papua New Guinea. This record shows that the Australian summer monsoon (ASM) intensity was influenced by combined precession and obliquity changes. The obliquity forcing could be primarily delivered by a cross-hemispherical thermal/pressure contrast, resulting from the asymmetric continental configuration between Asia and Australia in a coupled East Asian-Australian circulation system. In this talk, I will also briefly introduce one of our recent studies on the stalagmite-inferred multidecadally-resolved geomagnetic record during 107-91 ka and an abrupt centennial polarity reversal event at 98 ka.