Meridional circulation during the Last Glacial Maximum explored through a combination of South Atlantic δ18O observations and a geostrophic inverse model
MetadataShow full item record
The vertical profile of meridional transport in the South Atlantic is examined by combining paleoceanographic observations with a geostrophic circulation model using an inverse method. δ18Ocalcite observations along the margins of the South Atlantic show that upper-ocean cross-basin differences were weaker during the Last Glacial Maximum (LGM) than the Holocene. The δ18Ocalcite observations can be explained by a shift of water-mass properties without any change in the overturning circulation. Alternatively, they may indicate a reduced LGM cross-basin density difference and, via the thermal wind relation, a reduced vertical shear. Model inversions of δ18Ocalcite are found to require meridional transports different from the modern only after three assumptions are made: temperature and salinity distributions are spatially smooth, the relationship between salinity and δ18Owater is linear and spatially invariant, and LGM temperatures are known to within 1°C along the margins. The last assumption is necessary because an independent constraint on temperature or salinity is required to determine density from δ18Ocalcite observations. δ18Ocalcite observations are clearly useful, but before any firm constraints can be placed on LGM meridional transport, it appears necessary to better determine the relationship between δ18Ocalcite and density.
Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 7 (2006): Q11N07, doi:10.1029/2006GC001383.
Suggested CitationArticle: Gebbie, Geoffrey A., Huybers, Peter, "Meridional circulation during the Last Glacial Maximum explored through a combination of South Atlantic δ18O observations and a geostrophic inverse model", Geochemistry Geophysics Geosystems 7 (2006): Q11N07, DOI:10.1029/2006GC001383, https://hdl.handle.net/1912/1373
Showing items related by title, author, creator and subject.
Lynch-Stieglitz, Jean; Curry, William B.; Oppo, Delia W.; Ninnemann, Ulysses S.; Charles, Christopher D.; Munson, Jenna (American Geophysical Union, 2006-10-03)The geostrophic shear associated with the meridional overturning circulation is reflected in the difference in density between the eastern and western margins of the ocean basin. Here we examine how the density difference ...
Inferring ocean circulation during the Last Glacial Maximum and last deglaciation using data and models Amrhein, Daniel E. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2016-09)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 ...
Dail, Holly J. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2012-09)This thesis focuses on ocean circulation and atmospheric forcing in the Atlantic Ocean at the Last Glacial Maximum (LGM, 18-21 thousand years before present). Relative to the pre-industrial climate, LGM atmospheric CO2 ...