Effects of Eddy‐Driven Subduction on Ocean Biological Carbon Pump

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 500to 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.

[1]  M. Lomas,et al.  Decoupling of net community and export production on submesoscales in the Sargasso Sea , 2015 .

[2]  H. Claustre,et al.  Substantial energy input to the mesopelagic ecosystem from the seasonal mixed-layer pump , 2016, Nature geoscience.

[3]  Alexander M. Chekalyuk,et al.  Mesoscale ocean fronts enhance carbon export due to gravitational sinking and subduction , 2017, Proceedings of the National Academy of Sciences.

[4]  M. Long,et al.  Mesoscale Effects on Carbon Export: A Global Perspective , 2018 .

[5]  R. Goericke,et al.  The role of subduction and gravitational sinking in particle export, carbon sequestration, and the remineralization length scale in the California Current Ecosystem , 2018 .

[6]  Thomas W. Trull,et al.  Understanding the export of biogenic particles in oceanic waters: Is there consensus? , 2007 .

[7]  J. McWilliams,et al.  Submesoscale Cold Filaments in the Gulf Stream , 2014 .

[8]  M. Lévy,et al.  Subduction of carbon, nitrogen, and oxygen in the northeast Atlantic , 2011 .

[9]  Dennis A. Hansell.  Recalcitrant dissolved organic carbon fractions. , 2013, Annual review of marine science.

[10]  L. Bopp,et al.  Physical pathways for carbon transfers between the surface mixed layer and the ocean interior , 2013 .

[11]  Nicholas R. Bates,et al.  Eddy/Wind Interactions Stimulate Extraordinary Mid-Ocean Plankton Blooms , 2007, Science.

[12]  Anthony J Richardson,et al.  Anticyclonic eddies are more productive than cyclonic eddies in subtropical gyres because of winter mixing , 2016, Science Advances.

[13]  T. DeVries,et al.  Efficient dissolved organic carbon production and export in the oligotrophic ocean , 2017, Nature Communications.

[14]  D. Siegel,et al.  Thorium-234 as a tracer of spatial, temporal and vertical variability in particle flux in the North Pacific , 2009 .

[15]  David A. Siegel,et al.  Global assessment of ocean carbon export by combining satellite observations and food‐web models , 2014 .

[16]  D. Steinberg,et al.  Zooplankton and the Ocean Carbon Cycle. , 2017, Annual review of marine science.

[17]  John P. Dunne,et al.  A synthesis of global particle export from the surface ocean and cycling through the ocean interior and on the seafloor , 2007 .

[18]  M. Lévy,et al.  Low‐frequency and high‐frequency oscillatory winds synergistically enhance nutrient entrainment and phytoplankton at fronts , 2017 .

[19]  Gurvan Madec,et al.  Large-scale impacts of submesoscale dynamics on phytoplankton: Local and remote effects , 2012 .

[20]  T. R. Anderson,et al.  Reconciliation of the carbon budget in the ocean’s twilight zone , 2014, Nature.

[21]  Laurent Bopp,et al.  Controlling factors of the oxygen balance in the Arabian Sea's OMZ , 2012 .

[22]  M. Heath,et al.  Seasonal copepod lipid pump promotes carbon sequestration in the deep North Atlantic , 2015, Proceedings of the National Academy of Sciences.

[23]  Reiner Schlitzer,et al.  Export Production in the Equatorial and North Pacific Derived from Dissolved Oxygen, Nutrient and Carbon Data , 2004 .

[24]  James C. McWilliams,et al.  Submesoscale currents in the ocean , 2016, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[25]  Adrian P. Martin,et al.  How does dynamical spatial variability impact 234Th-derived estimates of organic export? , 2012 .

[26]  J. Greenwood,et al.  Impact of eddies on surface chlorophyll in the South Indian Ocean , 2014 .

[27]  Christoph Heinze,et al.  Multiple stressors of ocean ecosystems in the 21st century: projections with CMIP5 models , 2013 .

[28]  Richard Sanders,et al.  Global patterns in efficiency of particulate organic carbon export and transfer to the deep ocean , 2012 .

[29]  M. Gehlen,et al.  Variable reactivity of particulate organic matter in a global ocean biogeochemical model , 2017 .

[30]  Adrian P. Martin,et al.  Bringing physics to life at the submesoscale , 2012 .

[31]  R. Benner,et al.  Rapid cycling of high-molecular-weight dissolved organic matter in the ocean , 1994, Nature.

[32]  Walker O. Smith,et al.  Temperature effects on export production in the open ocean , 2000 .

[33]  P. Falkowski,et al.  Biogeochemical Controls and Feedbacks on Ocean Primary Production , 1998, Science.

[34]  H. Ducklow,et al.  Stirring Up the Biological Pump: Vertical Mixing and Carbon Export in the Southern Ocean , 2017 .

[35]  M. Gehlen,et al.  Slow‐sinking particulate organic carbon in the Atlantic Ocean: Magnitude, flux, and potential controls , 2017 .

[36]  Dennis A. Hansell,et al.  Dissolved Organic Matter in the Ocean: A Controversy Stimulates New Insights , 2009 .

[37]  S. Henson,et al.  High‐Frequency Variability of Small‐Particle Carbon Export Flux in the Northeast Atlantic , 2018, Global biogeochemical cycles.

[38]  Mary Jane Perry,et al.  Eddy-driven subduction exports particulate organic carbon from the spring bloom , 2015, Science.

[39]  Patrice Klein,et al.  Impact of sub-mesoscale physics on production and subduction of phytoplankton in an oligotrophic regime , 2001 .

[40]  Dennis A. Hansell,et al.  Biogeochemistry of marine dissolved organic matter , 2002 .

[41]  M. Lévy,et al.  Grid degradation of submesoscale resolving ocean models: Benefits for offline passive tracer transport , 2012 .

[42]  T. Jickells,et al.  Temporal and spatial variability of biogenic particles fluxes during the JGOFS northeast Atlantic process studies at 47°N, 20°W , 1994 .

[43]  J. Marshall,et al.  Observed mesoscale eddy signatures in Southern Ocean surface mixed-layer depth: SOUTHERN OCEAN EDDY MIXED-LAYER DEPTHS , 2017 .

[44]  Lars Stemmann,et al.  The wineglass effect shapes particle export to the deep ocean in mesoscale eddies , 2016 .

[45]  A. Mahadevan,et al.  Impact of episodic vertical fluxes on sea surface pCO2 , 2011, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[46]  Richard Sanders,et al.  A reduced estimate of the strength of the ocean's biological carbon pump , 2011 .

[47]  C. L. Leonard,et al.  Mesoscale Eddies Drive Increased Silica Export in the Subtropical Pacific Ocean , 2007, Science.

[48]  D. McGillicuddy,et al.  Mechanisms of Physical-Biological-Biogeochemical Interaction at the Oceanic Mesoscale. , 2016, Annual review of marine science.

[49]  Amala Mahadevan,et al.  The Impact of Submesoscale Physics on Primary Productivity of Plankton. , 2016, Annual review of marine science.

[50]  P. Strutton,et al.  Evaluating Southern Ocean Carbon Eddy‐Pump From Biogeochemical‐Argo Floats , 2018 .

[51]  A. Thompson,et al.  The Seasonality of Physically Driven Export at Submesoscales in the Northeast Atlantic Ocean , 2018, Global Biogeochemical Cycles.

[52]  S. Doney,et al.  Does eddy-eddy interaction control surface phytoplankton distribution and carbon export in the North Pacific Subtropical Gyre? , 2012 .

[53]  A. Alldredge,et al.  The physical strength of marine snow and its implications for particle disaggregation in the ocean , 1990 .

[54]  T. DeVries,et al.  The export and fate of organic matter in the ocean: New constraints from combining satellite and oceanographic tracer observations , 2017 .

[55]  Gurvan Madec,et al.  Modifications of gyre circulation by sub-mesoscale physics , 2010 .

[56]  H. Claustre,et al.  Multi-faceted particle pumps drive carbon sequestration in the ocean , 2019, Nature.