CO₂ deposition over the multi‐year ice of the western Weddell Sea

Field measurements by eddy correlation (EC) indicate an average uptake of 0.6 g CO 2 m −2 d −1 by the ice‐covered western Weddell Sea in December 2004. At the same time, snow that covers ice floes of the western Weddell Sea becomes undersaturated with CO 2 relative to the atmosphere during early summer. Gradients of CO 2 from the ice to the atmosphere do not support significant diffusive fluxes and are not strong enough to explain the observed CO 2 deposition. We hypothesize that the transport of air through the snow pack is controlled by turbulence and that undersaturation of CO 2 is caused by biological productivity at the ice‐snow and snow‐atmosphere interface. The total carbon uptake by the multi‐year ice zone of the western Weddell Sea in December could have been as high as 6.6 Tg C y −1 .