Phase Synchronization Between Polar Climates: its Identification, Evolution, and Connection to the Abrupt Warming Events of the Last Glacial Period Public Deposited

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  • March 19, 2019
Creator
  • Yang, Xiao
    • Affiliation: College of Arts and Sciences, Department of Geological Sciences
Abstract
  • During the last glacial period, warming events with different characteristics occurred on each Polar Region. In the Greenland records, the warming episodes, are abrupt and strong. In contrast, the Antarctic events of the same age are gradual and mild. While it is generally accepted that these events have a one-to-one relationship, their exact linkage mechanism remains unknown. In the following text, I have organized my research findings into three chapters, with each presenting a unique aspect of the polar climate relationship. In the first chapter, I associated the polar climates and their synchronization relation to the massive ice rafted detritus deposits (Heinrich events and IRD events) found across North Atlantic. Assuming the validity of the recent hypothesis of phase synchronization between polar records, I was able to develop indices that hindcast the timings of the Heinrich events. I then discussed the potential physical mechanisms that could connect the changes in the polar climates to the Heinrich events. In the second chapter, I conducted an inter-comparison study of all relevant published models, that seek to explain the polar climate connection, based on both their mathematical model properties, and their skills in reproducing actual records. Through the comparison, I demonstrated that the phase synchronization model exceeds the other two in its ability to reproduce actual records. While proposing the phase synchronization as a favorable framework, I also discussed the potential mechanism that integrates the phase synchronization and thermal bipolar seesaw models. After established the phase synchronization as the most accurate and robust model, in my third and last chapter, I extracted the variations in the strength of the phase synchronization by calculating the windowed mean phase coherence between the polar ice core records. My results revealed that, with strong phase coherence during majority of the glacial period, instances of weak coherence did happen. More importantly, further analysis revealed a persistent insolation lead over the variations in phase coherence. This discovery provides new ways of interpreting not only the polar climate relationship itself, but also the origin of the glacial warming events.
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Rights statement
  • In Copyright
Advisor
  • Pavelsky, Tamlin
  • West, J. Jason
  • Rial, Jose
  • Lees, Jonathan
  • Surge, Donna M.
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2016
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