Effects of Eddy‐Driven Subduction on Ocean Biological Carbon Pump

Abstract

Estimates of the ocean biological carbon pump are limited by uncertainties in the magnitude of the physical injection of particulate and dissolved organic carbon to the ocean interior. A major challenge is to evaluate the contribution of these physical pumps at small spatial and temporal scales (<100 km and <1 month). Here, we use a submesoscale permitting biophysical model covering a large domain representative of a subpolar and a subtropical gyre to quantify the impact of small‐scale physical carbon pumps.The model successfully simulates intense eddy‐driven subduction hot spots with a magnitude comparable to what has been observed in nature (1,000–6,000 mg C·m−2·day−1). These eddy‐driven subduction events are able to transfer carbon below the mixed‐layer, down to 500‐ to 1,000‐m depth. However, they contribute <5% to the annual flux at the scale of the basin, due to strong compensation between upward and downward fluxes. The model also simulates hot spots of export associated with small‐scale heterogeneity of the mixed layer, which intermittently export large amounts of suspended particulate and dissolved organic carbon. The mixed‐layer pump contributes ∼20% to the annual flux. High‐resolution measurements of export flux are needed to test models such as this one and to improve our mechanistic understanding of the biological pump and how it will respond to climate change.

Vertical eddy iron fluxes support primary production in the open Southern Ocean

“…There has been growing evidence regarding the relative importance of eddies in the biological carbon pump [46][47][48] . The eddies responsible for supplying iron also export phytoplankton downwards in our simulation.…”

Variability in Water-Column Respiration and Its Dependence on Organic Carbon Sources in the Canary Current Upwelling Region

“…The offshore transport is largely mediated by the numerous upwelling filaments (Gabric et al, 1993;García-Muñoz et al, 2004Santana-Falcón et al, 2016 and filamenteddy interactions, produced particularly south of the Canaries Archipelago (Arístegui et al, 2004(Arístegui et al, , 2009. Mesoscale eddies would transport organic carbon to the mesopelagic zone, by means of physical processes (e.g., Omand et al, 2015;Resplandy et al, 2019), explaining the high concentrations and irregular peaks of POC sus (and ETS activity) in deep layers observed at most of the stations. Recently, Amos et al (2019) used satellite-derived measurements of POC to show that mesocale eddies generated from meanders in the California Current, trap organic carbon and transport it as far as 1000 km offshore, greatly enriching the open ocean waters.…”

The Influence of Submesoscales and Vertical Mixing on the Export of Sinking Tracers in Large-Eddy Simulations

“…By convention we take w s , 0 so that the particles move down relative to the fluid. A similar approach is often used to simulate sinking particles in biogeochemical models (e.g., Resplandy et al 2019).…”