Multi-decadal trends in the advection and mixing of natural carbon in the Southern Ocean

Multi-decadal trends in the advection, mixing, and air-sea flux of natural carbon dioxide (CO2) in the Southern Ocean are investigated using output from a hindcast simulation of a non-eddy-resolving ocean model. Particular emphasis is placed on the model's improved eddy-induced advection parameterization. From 1958 to 2007, the model predicts a significant increase in the outgassing of natural CO2 from the Southern Ocean, congruent with a positive trend in the wind speed over this period. The natural CO2 flux trend is largely driven by enhanced Eulerian-mean advection and diapycnal mixing of dissolved inorganic carbon (DIC) into the Southern Ocean surface. The natural CO2 flux trend would be larger, if not for an increase in the eddy-induced advection of DIC out of the Southern Ocean surface, caused by the multi-decadal increase in the model's eddy-induced advection coefficient. Citation: Lovenduski, N. S., M. C. Long, P. R. Gent, and K. Lindsay (2013), Multi-decadal trends in the advection and mixing of natural carbon in the Southern Ocean, Geophys. Res. Lett., 40, 139-142, doi:10.1029/2012GL054483.