[U-03] Advanced understanding of Quaternary and Anthropocene hydroclimate changes in East Asia

[U03-P10] Meridional migrations of the Intertropical convergence Zone during the last deglaciation in the Timor Sea detected by extensive radiocarbon dating

*Karin Nemoto^1,2, Yusuke Yokoyama^1,2,3,4,5, Satoshi Horiike¹, Stephen Obrochta⁶, Yosuke Miyairi¹ (1.Atmosphere and Ocean Research Institute, University of Tokyo, 2.Department of Earth and Planetary Science, The University of Tokyo, 3.Graduate Program on Environmental Sciences, The University of Tokyo, 4.Japan Agency for Marine-Earth Science and Technology, 5.The Australian National University, 6.Graduate School of International Resource Science, Akita University)

Keywords:ITCZ, Be, deglaciation, radiocarbon dating

At the Intertropical Convergence Zone (ITCZ), the northern and southern Tradewinds converge, and this region is characterized by low atmospheric pressure and high precipitation. The climate in the Timor Sea is characterized by seasonal precipitation changes driven by meridional migrations of the ITCZ and the monsoonal front. The ITCZ shifts in response to changes in the thermal balance between the northern and southern hemispheres. Thus, reconstruction of paleo-precipitation in the Timor Sea is expected to reveal past changes in both regional and global climate, the latter through inference of the ITCZ position. To reconstruct paleo-precipitation in the Timor Sea, we performed extensive radiocarbon analysis on both planktonic foraminifera and total organic carbon (TOC), which is derived from terrestrial and marine sources. Increased precipitation enhances the fraction of relatively old, terrestrial carbon to the core site, which in turn increases the difference between the ages of TOC and planktonic foraminifera. Variations in radiocarbon ages reveal that during northern hemisphere cooling intervals such as Heinrich Stadial 1 and the Younger Dryas, the ITCZ was in a southern position, thus increasing precipitation in the Timor Sea. However, the Timor Sea was dryer during the Bølling–Allerød warming as the ITCZ shifted northward.