Down‐welling circulation of the northwest European continental shelf: A driving mechanism for the continental shelf carbon pump

Annually integrated measurements of pCO 2 have demonstrated that seasonally stratified regions of temperate shelf seas can be an important sink of atmospheric CO 2 . A key process to support this sink is the transport of carbon from shelf seas to below the permanent pycnocline of the deep ocean. Using a hydrodynamic model simulation of the northwest European Continental shelf, we find that both the large scale circulation and frictional processes support the off‐shelf transport of carbon sufficiently quickly to remove ∼40% of the carbon sequestered by one growing season before the onset of the next. This transport is highly heterogeneous, with some regions being only weakly flushed. Only 52% of this exported carbon is transported below the permanent pycnocline, hence the shelf sea and open ocean carbon cycles are intrinsically coupled.