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13 C constraints on ocean carbon cycle models
Author(s) -
Sonnerup Rolf E.,
Quay Paul D.
Publication year - 2012
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2010gb003980
Subject(s) - north atlantic deep water , deep sea , carbon cycle , oceanography , environmental science , ocean current , lead (geology) , deep water , ocean general circulation model , total organic carbon , climatology , geology , atmospheric sciences , climate change , general circulation model , chemistry , ecosystem , ecology , paleontology , biology , environmental chemistry
The sensitivity of oceanic δ 13 C fields to overturning and gas exchange is investigated in a suite of ocean general circulation models. The deep and oceanic mean δ 13 C in the models was sensitive to the balance between deep waters forming in the North Atlantic and the Southern Ocean. Increasing the Southern Ocean deep water formation rate to improve deep sea 14 C and AOU fields was detrimental to model‐data δ 13 C fidelity. A concurrent increase in North Atlantic Deep water would be needed to match the observed 14 C and δ 13 C, constraining both the rate and schematics of model deep water formation, respectively, and improving sensitivity to future perturbations. Inter‐basin trends in δ 13 C were sensitive to the rate of overturning in the models, with ‘high mixing’ model configurations matching the observations best. Models' anthropogenic δ 13 C changes, used as a diagnostic of model CO 2 uptake, were in agreement with the observations, except at high southern latitudes (<50°S), where the model δ 13 C changes were greater than observed. There were predictive relationships among models' uptake of anthropogenic CO 2 and depth‐integrated δ 13 C changes. Model relationships between model anthropogenic CO 2 uptake and the air‐sea δ 13 C disequilibrium, and the sea surface δ 13 C, depend on preindustrial riverine fluxes of terrestrial organic carbon, and on the wind field used to drive the model circulation, respectively. Among the models tested, the relations among anthropogenic CO 2 uptake and δ 13 C changes in the ocean are biased by the OCMIP practice of driving model momentum with one wind field, and gas exchange rates with another.