PhD Oral Defense of Yuan Shufang: Hydroclimate changes in the Maritime Continent over the past 30,000 years recorded by speleothems from Sulawesi, Indonesia

PhD Oral Defense of Yuan Shufang: Hydroclimate changes in the Maritime Continent over the past 30,000 years recorded by speleothems from Sulawesi, Indonesia

Event Type: 

  • Oral Defense

Venue: 

ASE 3D Visualisation Laboratory (N2-B1c-16c)

Date: 

13 March, 2019 - 10:00 to 12:30

About the Event: 

Atmospheric deep convection in the Maritime Continent (also manifested as the regional Inter-tropical Convergence Zone, or ITCZ) and its changes substantially impact the global heat and moisture budgets. However, our understanding of the variability of this deep convection is hindered by large discrepancies among paleo-records in the region regarding the millennial-to-orbital scale hydroclimate changes. To reconcile the discrepancies, in my thesis, I establish a new hydroclimate record using speleothem oxygen isotopic ratios (δ18O) from southwestern Sulawesi, Indonesia, and I further synthesize existing regional speleothem δ18O records. The synthesis allows me to constrain the mean position of the regional ITCZ, and derive an ITCZ migration index. I apply the index to other low-latitude speleothem δ18O records and reveal the mechanisms driving tropical hydroclimate changes since the Last Glacial Maximum (LGM). These findings contribute to our understanding of ITCZ variability and hence of regional-to-global hydroclimate variation. They also provide a reference for evaluating climate model simulations, and thus help predict future hydroclimate changes in the tropics.

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Members of the Examination Committee:

  • Professor Gideon Henderson (External Examiner), Oxford University, United Kingdom
  • Professor James Russell (External Examiner), Brown University, USA
  • Professor Edgardo Latrubesse (Internal Examiner), Nanyang Technological University, Singapore

Oral Examination Committee:

  • Associate Professor Qin Xiaosheng (Chairman), Nanyang Technological University, Singapore
  • Professor Edgardo Latrubesse (Oral Examiner), Nanyang Technological University, Singapore 
  • Associate Professor Adam Switzer (Oral Examiner), Nanyang Technological University, Singapore
  • Associate Professor Nathalie Goodkin (Oral Examiner), Nanyang Technological University, Singapore
  • Associate Professor Wen Yonggang (Oral Examiner), Nanyang Technological University, Singapore
  • Professor Gideon Henderson (Oral Examiner), Oxford University, United Kingdom

Advisors:

  • Assistant Professor Wang Xianfeng, Nanyang Technological University, Singapore
  • Associate Professor Nathalie Goodkin, Nanyang Technological University, Singapore
  • Associate Professor Wen Yonggang, Nanyang Technological University, Singapore

About the Speaker: 

Yuan Shufang

Yuan Shufang is a PhD candidate at the Interdisciplinary Graduate School (IGS), Asian School of the Environment (ASE), and Earth Observatory of Singapore (EOS), NTU. She received a BSc in Environmental Science from Tianjin University, China. She then obtained her MSc in Environmental Science from the Research Center for Eco-Environmental Science, Chinese Academy of Sciences. Since 2013, she has been conducting her research under the supervision of Assistant Professor Wang Xianfeng. In her PhD work, she has used speleothems (cave carbonates) to investigate the atmospheric deep convection and vegetation changes in the Maritime Continent. She has also synthesized regional and global speleothem δ18O records to better understand the forcing mechanisms of large-scale hydroclimate changes. More specifically, she has constrained the mean position of the ITCZ in the Maritime Continent and derived an index of ITCZ migration.

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