Fig. 3.

Influence of biology on air–sea CO₂ exchange in the SO. Meridional pattern of (A) seasonal SST range, annual average wind speed, and percentage sea ice cover; (B) average sea–air pCO₂ difference (ΔpCO₂ = pCO_{2 sea} − pCO_{2 air}); and (C) cumulative CO₂ flux over the productive (P) and unproductive seasons (U) for the different productivity scenarios, with annual results shown in subpanels. The shading and error bars reflect the propagated uncertainty. Frontal zones as described in Fig. 1. Positive values in B and C indicate a source of CO₂ to the atmosphere. Abiotic: reconstructed, abiotic ocean; TOM only: reconstructed ocean with only total organic carbon production; Observed: observed, biotic ocean including both TOM and PIC production.