[U-05] Advanced understanding of Quaternary and Anthropocene hydroclimate changes in East Asia

[U05-P08] The position, width, and intensity changes of the Intertropical Convergence Zone since the Last Glacial Maximum

*SHUFANG YUAN¹, Xianfeng Wang^1,2, Hong-Wei Chiang³, Guangxin Liu⁸, Satria Bijaksana⁴, Xiuyang Jiang⁵, Imran Umar⁶, Satrio Wicaksono⁷, Shaoneng He¹ (1.Earth Observatory of Singapore, 2.Nanyang Technological Univ., 3.National Taiwan Univ., 4.Bandung Institute of Technology, 5.Fujian Normal Univ., 6.Hasanuddin Univ., 7.Brown Univ., 8.Yunnan Univ.)

Keywords:ITCZ, Maritime Continent, speleothem δ18O

The intertropical convergence zone (ITCZ) plays a key role in regulating tropical hydroclimate and global water cycle through its latitudinal movement and rainfall intensity change. The long-term variability of the ITCZ, including its strength, position, and width changes, along with the corresponding driving mechanisms, however, remains ambiguous. Here we incorporate a new speleothem oxygen isotope (δ¹⁸O) record from southwestern Sulawesi, Indonesia with speleothem δ¹⁸O records from the Maritime Continent. Based on the absolute speleothem δ¹⁸O distribution, we constrain the latitudinal movements of the mean ITCZ within 3° during the past 30,000 years. We further characterize the width changes and latitudinal movements of the ITCZ respectively using the spatial gradients of δ¹⁸O between central and marginal ITCZ, and between marginal ITCZ and further beyond. Our results validate the energetic framework in driving both dynamics of the ITCZ, with alternating roles of interhemispheric thermal contrast and convection strength dominating the width changes. Furthermore, our reconstructions evidence profound tropical hydroclimate changes associated with intensified ITCZ and ENSO coupling during the mid-to-late Holocene.