Continental Shelf Pump - Overview

Overview

Originally formulated by Tsunogai et al. (1999), the pump is believed to occur where the solubility and biological pumps interact with a local hydrography that feeds dense water from the shelf floor into sub-surface (at least subthermocline) waters in the neighbouring deep ocean. Tsunogai et al.'s (1999) original work focused on the East China Sea, and the observation that, averaged over the year, its surface waters represented a sink for carbon dioxide. This observation was combined with others of the distribution of dissolved carbonate and alkalinity and explained as follows :

• the shallowness of the continental shelf restricts convection of cooling water
• as a consequence, cooling is greater for continental shelf waters than for neighbouring open ocean waters
• this leads to the production of relatively cool and dense water on the shelf
• the cooler waters promote the solubility pump and lead to an increased storage of dissolved inorganic carbon
• this extra carbon storage is augmented by the increased biological production characteristic of shelves
• the dense, carbon-rich shelf waters sink to the shelf floor and enter the sub-surface layer of the open ocean via isopycnal mixing