A box model test of the freshwater forcing hypothesis of abrupt climate change and the physics governing ocean stability
Figure S1: Comparison between solutions from 4-box model inversions (dashed) and results of Knutti et al.  (solid). (345.0Kb)
Figure S2: Equilibrium solutions of the 4-box ocean model with a parameterization of the Southern Ocean according to Gnanadesikan . (428.1Kb)
Figure S3: Inversion solutions for the 6-box model, with two boxes in each polar region and a stability threshold for deep convection in these regions. (360.3Kb)
Jackson, Charles S.
Thompson, William G.
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Observations and an ocean box model are combined in order to test the adequacy of the freshwater forcing hypothesis to explain abrupt climate change given the uncertainties in the parameterization of vertical buoyancy transport in the ocean. The combination is carried out using Bayesian stochastic inversion, which allows us to infer changes in the mass balance of Northern Hemisphere (NH) ice sheets and in the meridional transports of mass and heat in the Atlantic Ocean that would be required to explain Dansgaard-Oeschger Interstadials (DOIs) from 30 to 39 kyr B.P. The mean sea level changes implied by changes in NH ice sheet mass balance agree in amplitude and timing with reconstructions from the geologic record, which gives some support to the freshwater forcing hypothesis. The inversion suggests that the duration of the DOIs should be directly related to the growth of land ice. Our results are unaffected by uncertainties in the representation of vertical buoyancy transport in the ocean. However, the solutions are sensitive to assumptions about physical processes at polar latitudes.
Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 25 (2010): PA4222, doi:10.1029/2010PA001936.
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