Modeling the Continental Shelf Pump for Dissolved Inorganic Carbon in the Chukchi Sea From 1998 to 2015

Quantifying the flux of dissolved inorganic carbon (DIC) from the Chukchi shelf to the deep ocean (i.e., the continental shelf pump) is of great significance for understanding the carbon cycle and ocean acidification in the changing Arctic Ocean. Using a coupled ocean-sea ice-biogeochemical model, this study shows that the Pacific inflow drives the highly efficient continental shelf pump in the Chukchi Sea, with a multi-year average of 828 Tg C-DIC exported to deep basins during 1998-2015. The Pacific annual inflow carries 385 Tg C-DIC to the Chukchi Sea in summertime (May-September) and 436 Tg C in wintertime (October-April). Downstream, DIC is mainly exported via Barrow Canyon (BC) (266 Tg C, 64%) in summer and along the shelf under the 100 m isobath (217 Tg C, 53%) in winter. This variability corresponds to the seasonal variation of local winds. The stronger winter northeasterly winds hinder the outflow through BC. In both seasons, interannual variability exists in the proportion of DIC exports through different pathways. The fraction of DIC export via BC has a significant correlation (r > 0.8) with the along-canyon wind speed. This is further related to the sea level pressure (SLP) gradient between the Arctic and North Pacific. A weaker SLP gradient leads to weaker local northeasterly wind, and thus favors a higher proportion of DIC export via BC and lower DIC export through other pathways. This process plays a key role in the redistribution of shelf-sourced DIC in deep basins of the Arctic Ocean.

Automated summary

This study demonstrates the role of Pacific inflow in driving the Chukchi shelf pump and quantifies the flux of DIC. The results also reveal the influence of seasonal and interannual variability on this process.