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Control of the glacial carbon budget by topographically induced mixing
Author(s) -
De Boer Agatha M.,
Hogg Andrew McC.
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl059963
Subject(s) - glacial period , geology , mixing (physics) , outcrop , ocean current , carbon cycle , water mass , bottom water , oceanography , deep sea , deep water , antarctic bottom water , climatology , atmospheric sciences , geomorphology , ecology , physics , quantum mechanics , ecosystem , biology
Abstract Evidence for the oceanic uptake of atmospheric CO 2 during glaciations suggests that there was less production of southern origin deep water but, paradoxically, a larger volume of southern origin water than today. Here we demonstrate, using a theoretical box model, that the inverse relationship between volume and production rate of this water mass can be explained by invoking mixing rates in the deep ocean that are proportional to topographic outcropping area scaled with ocean floor slope. Furthermore, we show that the resulting profile, of a near‐linear decrease in mixing intensity away from the bottom, generates a positive feedback on CO 2 uptake that can initiate a glacial cycle. The results point to the importance of using topography‐dependent mixing when studying the large‐scale ocean circulation, especially in the paleo‐intercomparison models that have failed to produce the weaker and more voluminous bottom water of the Last Glacial Maximum.