Effects of Eddy‐Driven Subduction on Ocean Biological Carbon Pump
Year: 2019
Type: article
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.
Source: Global Biogeochemical Cycles
DOI: 10.1029/2018gb006125
Institutions: Princeton University, High Meadows Environmental Institute, Centre National de la Recherche Scientifique, Sorbonne Université, Institut Pierre-Simon Laplace, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques, Institut de Recherche pour le Développement, Woods Hole Oceanographic Institution
Language: English
Subfield: Oceanography
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
Awards: Southern Ocean Biogeochemistry Under Multiple Stressors, THE PHYSICAL, BIOLOGICAL AND GEOCHEMICAL PROCESSES THAT LEAD TO THE TRANSFER OF CARBON FROM THE SURFACE TO THE DEEP OCEAN VIA THE BIOLOGICAL PUMP VAR, THE PRIMARY GOAL OF THE EXPORTS PROCESSES IN THE OCEAN FROM REMOTE SENSING (EXPORTS) PROGRAM IS TO DEVELOP A PREDICTIVE MECHANISTIC UNDERSTANDING OF THE EXPORT AND FATE OF FIXED CARBON (C) FROM GLOBAL OCEAN PRIMARY PRODUCTION. INHERENT IN THESE PREDICTIONS IS THE NEED TO REDUCE UNCERTAINTIES IN C EXPORT AND TO DEVELOP MODELS THAT FACILITATE FUTURE C EXPORT PREDICATIONS ACROSS A VARIETY OF SPATIAL AND TEMPORAL SCALES. THE FIRST PHASE INCLUDES LARGE-SCALE FIELD CAMPAIGNS USING REMOTE SENSING AUTONOMOUS PLATFORMS AND PROCESS-LEVEL STUDIES TO BUILD UPON CURRENT KNOWLEDGE. AS SUCH CRITICAL COMPONENTS TO THE EXPORTS PROGRAM ARE QUANTITATIVE MEASUREMENTS OF SINKING PARTICLE FLUXES AND THEIR ATTENUATION AT SCALES SIMILAR TO THE PHYSICAL AND BIOLOGICAL PROCESSES THAT INFLUENCE FIXED C EXPORT. WE PROPOSE USING THE PARTICLE-REACTIVE TRACER THORIUM-234 (HALF-LIFE = 24. 1 D) TO QUANTIFY THE SPATIO-TEMPORAL VARIABILITY IN PARTICLE FLUX FROM THE WELL-LIT SURFACE LAYER AND ITS ATTENUATION WITH DEPTH BELOW. THE DISEQUILIBRIUM IN 234TH FROM ITS SOLUBLE PARENT URANIUM-238 PROVIDES QUANTITATIVE INFORMATION ON WHERE PARTICLE EXPORT AND REMINERALIZATION OCCURS. WE WILL COLLECT AN UNPRECEDENTED SET OF 234TH PROFILES ( 60) TO OBTAIN A 3D TIME-SERIES OF PARTICLE EXPORT AND REMINERALIZATION RATES OVER MESO- (~ 10 KM) AND SUBMESOSCALES (~ 1 KM).
OpenAlex ID: W2966874637