Quantification of Chaotic Intrinsic Variability of Sea-Air CO₂ Fluxes at Interannual Timescales

Chaotic intrinsic variability (CIV) emerges spontaneously from nonlinear ocean dynamics even without any atmospheric variability. Eddy-permitting numerical simulations suggest that CIV is a significant contributor to the interannual to decadal variability of physical properties. Here we show from an ensemble of global ocean eddy-permitting simulations that large-scale interannual CIV propagates from physical properties to sea-air CO₂ fluxes in areas of high mesoscale eddy activity (e.g., Southern Ocean and western boundary currents). In these regions and at scales larger than 500 km (~5°), CIV contributes significantly to the interannual variability of sea-air CO₂ fluxes. Between 35°S and 45°S (midlatitude Southern Ocean), CIV amounts to 23.76 TgC yr^-1 or one half of the atmospherically forced variability. Locally, its contribution to the total interannual variance of sea-air CO₂ fluxes exceeds 76%. Outside eddy-active regions its contribution to total interannual variability is below 16%.