Carbon pathways in the South Atlantic

Transcription

1 Carbon pathways in the South Atlantic Olga T. Sato, Ph.D. Paulo Polito, Ph.D. - Oceanographic Institute University of São Paulo Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 1 / 16

2 Outline 1 Introduction The Program Scientific Interest Study areas Brazilan Continental Shelves The conceptual models Circulation study Lagrangian drifters Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 2 / 16

3 Outline Introduction 1 Introduction The Program Scientific Interest Study areas Brazilan Continental Shelves The conceptual models Circulation study Lagrangian drifters Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 3 / 16

4 The Program CARBOM-OCEANS This initiave is part of a master project submitted to the Brazilian Federal Agency - CNPq Environmental Characterization and Evaluation of Biogenic Ocean Resources from the Brazilian Continental Shelf and Adjacent Oceanic Zone - CARBOM OCEANS Coordination: University of São Paulo (USP) Main theme: the budget of carbon and chemical elements associated with the production of organic matter in the South Atlantic ocean, as well as the annual flux between biogeochemical compartments of the Brazilian continental margin and adjacent deep ocean areas Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 4 / 16

5 Scientific Hypothesis Introduction Scientific Interest One of the scientific hypothesis of the project is: The origin of most of the organic matter in the Brazilian Southeastern Continental Shelf (SECS) is in the South Atlantic Central Water (SACW). Thus, the physical processes that induce the intrusion of this body of water toward the coast determine the fertilization of the euphotic zone and maintain a working ecosystem in this sector of the Brazilian continental shelf. Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 5 / 16

6 Study areas Study area: NE and SE Shelves Inventory of carbon at the Brazilian NE and SE continental shelves and its adjacent oceanic regions. Strategic interest for the marine conservation in the South Atlantic and Equatorial regions and for a sustainable exploitation of mineral and biotechnological resources. Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 6 / 16

7 Study areas Identifying the sources of carbon In the SE: Besides the continental drainage, atmospheric inputs, and in situ regeneration by microbial processes, the source of the nutrients in the SECS is of oceanic origin: the SACW. Analyze the effects of typical SACW intrusions over most of the SECS on the carbon flux and on the functioning of their ecosystems; In the NE: The prevailing trade winds prevent SACW intrusions nearly shielding the NECS to the presence of nutrient-rich ocean waters. Despite the continental drainage, the region is oligotrophic with low primary production in the pelagic system. Most of the autotrophic carbon assimilation occurs in the benthic system, mainly in the calcareous algae, ccorals, molluscs, and foraminifera. Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 7 / 16

8 Study areas Focusing on the dynamics of SECS Several meso to large-scale physical mechanisms, still not fully understood, ensure the fertilization of the euphotic zone in the SECS by conveying the SACW from the slope to near the coast; Transport due to the wind drift in the surface layer is toward the sea while an adjustment transport over the entire water column is in the opposite direction; Depending on the position of meanders or eddies with respect to the continental shelf, there is possibility of SACW pumping toward the surface, facilitating the work of the NE-E winds to carry the SACW toward the coast; Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 8 / 16

9 Brazilan Continental Shelves Southeastern Continental Shelf - SECS Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 9 / 16

10 Conceptual Model Introduction The conceptual models Biogeochemical and physical processes in the SE continental shelf. Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 10 / 16

11 The conceptual models Northeastern Continental Shelf - NECS Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 11 / 16

12 Circulation study Circulation and material transport The role of along-shore advection due to mean current patterns and cross-shelf exchanges between coastal and open oceans must be better understood to describe the biogeochemical cycle in the ocean properly, which will be addressed using: 1 CTD profiling 2 ADCP 3 Glider 4 Moored stations 5 Lagrangian drifters 6 Satellite 7 Modelling Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 12 / 16

13 Lagrangian drifters Use of lagrangian drifters The use of particles that follow the flow, i.e. motion from a Lagrangian point of view, introduces valuable information of the variability at sub-inertial frequencies which, in turn, are useful to improve physical-biological models. The advantage of the description of particle motion is their ability to capture spatio temporal details of the flow while measurements from hydrographic sections and moorings are fixed in time and space respectively. Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 13 / 16

14 Lagrangian drifters Large scale and long term experiment Groups of Argo profilers will be launched simultaneously and programmed to derive at different depths, e.g. 500, 1000, 1500 and 2000 m. Investigate the divergence and convergence of the mass flux. The trajectories at different levels will provide a description of the baroclinicity of the flow responsible for the transport of organic and inorganic materials in the ocean. In particular, we are interested in deploying the profiling floats on regions where satellite images indicate the presence of meanders and eddies. The vertical velocity anisotropy of these features can significantly change the final destination of particles carried by the flow from a common geographic point of origin. Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 14 / 16

15 Lagrangian drifters The Field Lab: Alpha Crucis Recently acquired oceanographic ship, Moana Wave, from University of Hawaii, will carry out the CARBOM mission. Open ocean research vessel, 211 ft (64m) long, displacing 972 metric tons, with 45 days of autonomy an capacity for 20 researchers. Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 15 / 16

16 Lagrangian drifters Thank You! Olga Sato and Paulo Polito (IOUSP) Carbon pathways in the South Atlantic 16 / 16