A global glacial ocean state estimate constrained by upper-ocean temperature proxies
Amrhein, Daniel E.
MetadataShow full item record
KeywordOcean; Abyssal circulation; Sea surface temperature; Paleoclimate; Inverse methods; Ocean models
We use the method of least squares with Lagrange multipliers to fit an ocean general circulation model to the Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface (MARGO) estimate of near sea surface temperature (NSST) at the Last Glacial Maximum (LGM; circa 23–19 thousand years ago). Compared to a modern simulation, the resulting global, last-glacial ocean state estimate, which fits the MARGO data within uncertainties in a free-running coupled ocean–sea ice simulation, has global-mean NSSTs that are 2°C lower and greater sea ice extent in all seasons in both the Northern and Southern Hemispheres. Increased brine rejection by sea ice formation in the Southern Ocean contributes to a stronger abyssal stratification set principally by salinity, qualitatively consistent with pore fluid measurements. The upper cell of the glacial Atlantic overturning circulation is deeper and stronger. Dye release experiments show similar distributions of Southern Ocean source waters in the glacial and modern western Atlantic, suggesting that LGM NSST data do not require a major reorganization of abyssal water masses. Outstanding challenges in reconstructing LGM ocean conditions include reducing effects from model biases and finding computationally efficient ways to incorporate abyssal tracers in global circulation inversions. Progress will be aided by the development of coupled ocean–atmosphere–ice inverse models, by improving high-latitude model processes that connect the upper and abyssal oceans, and by the collection of additional paleoclimate observations.
Author Posting. © American Meteorological Society, 2018. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 31 (2018): 8059-8079, doi:10.1175/JCLI-D-17-0769.1.
Suggested CitationArticle: Amrhein, Daniel E., Wunsch, Carl, Marchal, Olivier, Forget, Gael, "A global glacial ocean state estimate constrained by upper-ocean temperature proxies", Journal of Climate 31 (2018): 8059-8079, DOI:10.1175/JCLI-D-17-0769.1, https://hdl.handle.net/1912/10576
Showing items related by title, author, creator and subject.
Mechanisms governing interannual variability of upper-ocean temperature in a global ocean hindcast simulation Doney, Scott C.; Yeager, Stephen G.; Danabasoglu, Gokhan; Large, William G.; McWilliams, James C. (American Meteorological Society, 2007-07)The interannual variability in upper-ocean (0–400 m) temperature and governing mechanisms for the period 1968–97 are quantified from a global ocean hindcast simulation driven by atmospheric reanalysis and satellite data ...
Emplacement and high-temperature evolution of gabbros of the 16.5 degrees N oceanic core complexes (Mid-Atlantic Ridge): Insights into the compositional variability of the lower oceanic crust. Sanfilippo, Alessio; Dick, Henry JB; Marschall, Horst R.; Lissenberg, C. Johan; Urann, Ben (American Geophysical Union, 2018-12-05)This study reports the composition of the oceanic crust from the 16.5°N region of the Mid‐Atlantic Ridge, a spreading ridge segment characterized by a complex detachment fault system and three main oceanic core complexes ...
Metrics of hurricane-ocean interaction : vertically-integrated or vertically-averaged ocean temperature? Price, James F. (Copernicus Publications on behalf of the European Geosciences Union, 2009-05-05)The ocean thermal field is often represented in hurricane-ocean interaction by a metric termed upper Ocean Heat Content (OHC), the vertical integral of ocean temperature in excess of 26°C. High values of OHC have proven ...