NSF Org: |
OPP Office of Polar Programs (OPP) |
Recipient: |
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Initial Amendment Date: | May 12, 2017 |
Latest Amendment Date: | May 12, 2017 |
Award Number: | 1643468 |
Award Instrument: | Standard Grant |
Program Manager: |
Peter Milne
OPP Office of Polar Programs (OPP) GEO Directorate For Geosciences |
Start Date: | May 15, 2017 |
End Date: | April 30, 2020 (Estimated) |
Total Intended Award Amount: | $125,460.00 |
Total Awarded Amount to Date: | $125,460.00 |
Funds Obligated to Date: |
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History of Investigator: |
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Recipient Sponsored Research Office: |
310 E CAMPUS RD RM 409 ATHENS GA US 30602-1589 (706)542-5939 |
Sponsor Congressional District: |
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Primary Place of Performance: |
310 East Campus Athens GA US 30602-1589 |
Primary Place of Performance Congressional District: |
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Unique Entity Identifier (UEI): |
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Parent UEI: |
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NSF Program(s): | ANT Ocean & Atmos Sciences |
Primary Program Source: |
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Program Reference Code(s): |
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Program Element Code(s): |
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Award Agency Code: | 4900 |
Fund Agency Code: | 4900 |
Assistance Listing Number(s): | 47.050 |
ABSTRACT
The Southern Ocean accounts for a large fraction of the global ocean CO2 uptake. The Southern Ocean is also unique because it encircles the globe, providing pathways for deep, inter-basin exchange. Previous studies have shown that particulate organic carbon (POC; fixed organic matter) seasonally builds up around the productive Antarctic seas before moving off-shore. The project will serve as a step toward better quantifying the export of POC from around the Antarctic Peninsula and better understanding the larger Southern Ocean carbon cycle. The project will promote education by supporting graduate and undergraduate students. New data sets on offshore transport pathways and POC variability will be generated in a consistent and systematic manner, and will be available to the scientific community.
This proposal will examine the offshore export of particulate organic carbon (POC) off the Antarctic Peninsula, from areas of high accumulation near the coast to areas offshore. We hypothesize that both wind-driven surface Ekman transport and transport by nonlinear mesoscale eddies can make significant contributions to the offshore export of POC. Specifically, the project will (1) identify areas of enhanced accumulation of POC off the Antarctic Peninsula; (2) quantify spatial and temporal variability in offshore transport by nonlinear mesoscale eddies and by winds in a surface Ekman layer; and (3) compare the estimates of offshore transport to the POC distribution away from the coast to identify preferred transport pathways or hotspots for offshore export of coastal water and POC off the Peninsula. This study will utilize decade-long satellite observations of POC based on algorithms validated against in situ data, ocean vector winds, eddy kinematic and propagation characteristics based on altimeter data, and results from a high resolution eddy resolving ocean model coupled to a sea ice model. The study will focus on the Antarctic Peninsula during summer, when reduced cloud/sea ice cover when satellite data availability is high.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Intellectual Merit: This award supported the investigation of the offshore transport of particulate organic carbon off the West Antarctic Peninsula, from areas of high accumulation near the coast to areas offshore. Particulate organic carbon contains both suspended and sinking particles, including most living cells in the ocean. The Southern Ocean is characterized by high eddy activity and high particulate organic carbon content during summer, especially near Antarctica. Because it encircles the globe, it provides a link for the exchange of water masses and climatically-significant quantities between the major ocean basins in the world. Thus, identifying mechanisms driving offshore transport of coastal water is important because they contribute to spreading that organic carbon over large areas of the Southern Ocean. In this project, satellite observations and in situ data have been combined with results from a high-resolution ocean model to quantify carbon transport off the West Antarctica Peninsula. Our analyses revealed that cyclonic eddies (rotating clockwise in the Southern Hemisphere) generated near the coast off the West Antarctica Peninsula often trap coastal water rich in particulate organic carbon during formation before propagating offshore. As a result, cyclones found offshore that were generated near the coast have on average higher particulate organic carbon content in their interior than cyclones generated locally offshore. This results in a particulate organic carbon enrichment of 5.9 +/- 1.4 Gg C per year in offshore waters off the Peninsula. Actual particulate organic carbon enrichment is likely substantially larger, since model results indicate that about half of the transport of coastal water is driven by small eddies that are missed by observations. Mesoscale eddies are ubiquitous features in the Southern Ocean and particulate organic carbon accumulation during summer is also observed in several other Antarctic coastal regions. These suggest that offshore transport of coastal water rich in particulate organic carbon by nonlinear eddies could be important throughout Antarctica. Our analysis also serves as an indicator of transport of other quantities that cannot be easily measured by satellites, such as freshwater from ice melting and nutrients.
Broader Impacts: This project supported the training of two graduate students. Findings supported by this study were described in four scientific articles (two published, two submitted) and were presented in various scientific conferences. Model outputs have been made publicly available at BCO-DMO (https://www.bco-dmo.org/project/821696).
Last Modified: 09/14/2020
Modified by: Patricia M Medeiros
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