When the mixed layer deepens, strong vertical gradients of DIC drive enhanced vertical diffusion of DIC at the base of the mixed layer. Thus, we analyzed a major determinant of the subsurface DIC supply at the Antartic Divergence, namely the balance of meridional fluxes of DIC. Meridional transport of DIC is computed as a function of potential density in the same way that many previous studies have computed volume transport [e.g., Hallberg and Gnanadesikan, 2006; Farneti et al., 2010]. Potential density is used rather than depth to better represent transport of water masses [e.g., Treguier et al., 2007]. Yet unlike volume transport, DIC transport cannot be described precisely by a stream function, because is divergent whereas is not. Strictly speaking, one cannot follow streamlines of the zonally averaged meridional DIC flux, but it is accurate to study the associated intensity and direction of the flux at a given latitude and density. To compute the total meridional flux of DIC, its transport is averaged zonally along constant potential density surfaces and then integrated vertically:
where σ2is the 2000 m reference potential density, H is the spatially varying bottom depth, and is the depth of the σ2isopycnal. The overbar denotes the time average over 1995–2004, while v is the 5 day-averaged meridional velocity and DIC refers to its concentration. To quantify how eddies affect the DIC response to the SAM, the total meridional flux of DIC is decomposed into three contributions following the approach for water transport [Dufour et al., 2012]:
The first component Γzonis the transport by the zonal mean flow, which is associated with the northward Ekman transport in shallow layers and the southward geostrophic transport in layers below the sill depth of Drake Passage. The second component ΓSEis the transport by standing eddies, defined as meridional deviations from a zonal mean. Standing eddy transport includes that from stationary meanders as well as the large-scale meanders of the ACC. The third component ΓTEis the transport from transient eddies, defined as deviations from the time mean following Treguier et al. . Transient eddy transport is that associated with time-varying features of ocean circulation (e.g., frontal waves, rings, eddies, and meanders).
 Figure 7 shows the result of this decomposition for both the reference simulation (REF05) and the anomaly (SAM05+++–REF05). In REF05, the total DIC flux (Γtot) displays a clockwise cell which extends up to ∼55°S and is called the subpolar cell. The subpolar cell corresponds to a circulation where DIC-rich NADW from the north are brought to the surface near the Antarctic Divergence by Ekman pumping, are transformed into AAIW by surface fluxes, and are returned north as intermediate waters. Here we thus focus on the subpolar cell because it is the cell-controlling DIC supply to the subsurface at the Antarctic Divergence.
 In REF05, the total DIC flux brought to the subsurface of the Antarctic Divergence reaches ∼7 Pg C yr−1. This total flux is mainly driven by the vigorous wind-driven DIC flux (Γzon) that reaches ∼22 Pg C yr−1and is centered at latitudes of the ACC. This wind-driven flux component comes up near the subsurface of the Antarctic Divergence and flows back northward, driven by Ekman pumping and Ekman transport in the Ekman layer. The two other components partially compensate the wind-driven DIC flux: The standing eddy-induced DIC flux (ΓSE) reaches its ∼22 Pg C yr−1maximum in shallow layers between 45°S and 60°S, while the transient eddy-induced DIC flux (ΓTE) reaches its ∼10 Pg C yr−1maximum in deeper layers between 40°S and 60°S. The compensation by the standing eddy component is likely from small-scale meanders rather than large-scale meanders or even basin-scale gyres [Ballarotta et al., 2013].
 Positive SAM events intensify the total meridional DIC flux by ∼2 Pg C yr−1, the final balance of the three stronger components. Simultaneously, there is a poleward shift of the subpolar cell by ∼2°–3°, corresponding to the poleward shift in the westerlies. A simple metric of the change in subpolar cell intensity is to average its DIC transport between 40°S and 60°S. With that, the anomaly in the total DIC flux increases by ∼6% std−1(SAM), with more brought to the subsurface near the Antarctic Divergence. The main driver is the wind-driven DIC flux that is intensified by ∼10% std−1(SAM), but that is partly compensated by the total eddy-induced DIC flux: the standing eddy component intensifies by ∼4% std−1(SAM) while the transient eddy component strengthens by ∼15% std−1(SAM). Overall, our intermediate-resolution model study suggests that about one third of the SAM-induced increase in wind-driven northward DIC flux is compensated by transport associated with standing and transient eddies.