Inferring ocean circulation during the last glacial maximum and last deglaciation using data and models
Name
971247903-MIT.pdf
Description
Full printable version
Size
21.11 MB
Format
Adobe PDF
Checksum (MD5)
4979100de9d26247b0c72784b382e8d5
Author(s)
Amrhein, Daniel Edward
Advisor(s)
Carl Wunsch.
Date Issued
February 22, 2017
Publisher
Massachusetts Institute of Technology
Abstract
Since the Last Glacial Maximum (LGM, ~ 20,000 years ago) air temperatures warmed, sea level rose roughly 130 meters, and atmospheric concentrations of carbon dioxide increased. This thesis combines global models and paleoceanographic observations to constrain the ocean's role in storing and transporting heat, salt, and other tracers during this time, with implications for understanding how the modem ocean works and how it might change in the future. -- By combining a kinematic ocean model with "upstream" and "downstream" deglacial oxygen isotope time series from benthic and planktonic foraminifera, I show that the data are in agreement with the modem circulation, quantify their power to infer circulation changes, and propose new data locations. -- An ocean general circulation model (the MITgcm) constrained to fit LGM sea surface temperature proxy observations reveals colder ocean temperatures, greater sea ice extent, and changes in ocean mixed layer depth, and suggests that some features in the data are not robust. -- A sensitivity analysis in the MITgcm demonstrates that changes in winds or in ocean turbulent transport can explain the hypothesis that the boundary between deep Atlantic waters originating from Northern and Southern Hemispheres was shallower at the LGM than it is today.
Description
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2016.
Ph. D. Joint Program in Oceanography (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2012
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 179-192).
Subjects
Joint Program in Oceanography.
Earth, Atmospheric, and Planetary Sciences.
Woods Hole Oceanographic Institution.
MIT Department
Joint Program in Oceanography
Woods Hole Oceanographic Institution
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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