Glob. Biogeochem. Cycles http://doi.org/cm9r (2018)

Carbon export in the ocean is linked to plankton productivity in the surface waters, yet ocean models are typically run at too coarse a resolution to capture mesoscale (10–100 km) ocean circulation. Circulation at this scale influences nutrient transport and plankton, so estimates from lower-resolution simulations may not accurately capture export production.

To address this issue, Cheryl Harrison of the National Center for Atmospheric Research and the University of Colorado, Boulder, USA, and co-authors use simulations at different resolutions, eddy-resolving (0.1°) and non-eddy-resolving (1°), in the Community Earth system Model. They find that the higher-resolution simulation shows a small (<2%) decrease when considering global export production, however at local scales there is a large ±50% variation due to regional effects.

In areas where off-shelf transport of nutrients drives productivity, improved representation of coastal jets, which block this transport, and turbulence results in lower export. In contrast, export is increased in the subantarctic due to a deeper and narrower mixed layer, capturing more nutrients that fuel higher production. These large regional differences that result from mesoscale circulation should be considered when calculating carbon export and budgets.