| NSF Org: |
OCE Division Of Ocean Sciences |
| Recipient: |
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| Initial Amendment Date: | August 8, 2024 |
| Latest Amendment Date: | August 8, 2024 |
| Award Number: | 2407468 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Timothy Crone
tjcrone@nsf.gov (703)292-4344 OCE Division Of Ocean Sciences GEO Directorate for Geosciences |
| Start Date: | November 1, 2024 |
| End Date: | October 31, 2026 (Estimated) |
| Total Intended Award Amount: | $417,619.00 |
| Total Awarded Amount to Date: | $417,619.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
266 WOODS HOLE RD WOODS HOLE MA US 02543-1535 (508)289-3542 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
Woods HOle MA US 02543-1126 |
| 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): | OCE Postdoctoral Fellowships |
| 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 plays a large role in the uptake of carbon from the atmosphere, buffering increased anthropogenic carbon dioxide emissions. This is possible in part by the growth of phytoplankton, which consume carbon dioxide as they photosynthesize at the surface of the ocean. Surface phytoplankton can be subducted into the depths of the ocean through physical ocean movements, storing their carbon away from the atmosphere. Physical ocean processes that allow phytoplankton to grow and physical ocean processes that subduct phytoplankton are especially prevalent at ocean fronts, where two water masses meet each other. However, these processes are often three-dimensional and/or short lived, making them hard to observed. This creates a knowledge gap in understanding of how these events contribute to the removal of carbon from the atmosphere. The prosed project will use high resolution data from several Southern Ocean fronts to define physical initiation mechanisms that signal the occurrence of phytoplankton production and then phytoplankton (carbon) export events from surface velocity fields that can be measured by satellites. Results from this project will close gaps in understanding of episodic contributions of Southern Ocean fronts to the global carbon cycle. Future work to incorporate these results into climate models will allow for more accurate representation of the carbon cycle, which will aid in the prediction of future climate. The use of open sourced and remotely sensed data in this project creates an avenue for participation in Southern Ocean science without physically traveling to the Southern Ocean, allowing for traditionally untapped talent to contribute. This project will include educational outreach by bringing data from this project into local middle schools. Working with science teachers, this project will develop data literacy curricula and visit local middle school science classrooms to execute these lessons. Lessons will empower students to visualize data trends and test their own hypotheses with provided data. These efforts will advance the field by encouraging future talent to partake in oceanography even if they are unable to physically travel to remote ocean regions.
The proposed project will investigate physical mechanisms that contribute to episodic primary production and subsequent carbon sequestration at ocean fronts within the Antarctic Circumpolar Current (ACC). Energetic frontal regions, characterized by three dimensional velocities, often trigger primary productivity by alleviating light and nutrient limitation through upwelling. Subduction at these dynamic fronts creates an active and fast pathway for the sequestration of carbon to depth. These events are sporadic and short lived, making them hard to observe. Within dynamic frontal regions, changes in the strain field can alter the horizontal density gradient, or the ?sharpness? of the front as well as associated vertical velocities. This project uses high- resolution data at three ACC fronts in conjunction with a novel application of a strain field diagnostic tool, Lyapunov Exponents, to investigate the physical mechanisms of this ephemeral primary production (upwelling) and carbon subduction (downwelling) events. The proposed dataset has already been collected by previous projects. A Video Plankton II was towed across the Polar, Subantarctic, and Agulhas Fronts observing phytoplankton biomass and particulate organic carbon (POC) while an Acoustic Current Doppler Profiler (ADCP) measured the vertical current structure of the fronts. Preliminary results show increases in phytoplankton biomass and POC associated with each front, but to varying degrees. This suggests that each front is in a different phase of episodic production and subduction of carbon. The Lyapunov Exponent tool proposed for use is a Finite Size Lyapunov Exponent (FSLE). FSLE will turn dynamic velocity fields (altimetry derived geostrophic flow) into mapped scalar quantities that describe transport barrier strength, changing in space and time. Previous work has found that areas with strong transport barriers are often associated with vertical velocities and increased bioactivity. The evolution of FSLE at each of these fronts will be compared with the extent of the increase in phytoplankton biomass and POC as well as the strength of upwelling/downwelling. This proposed work will (1) describe the relationship between the strain field at fronts and ephemeral increases in primary production and carbon subduction (2) provide a three-dimensional analysis of biophysical interactions at transport barriers to a traditionally two-dimensional technique (FSLE) and (3) deepen understanding of the contribution of fronts to the Southern Ocean carbon cycle. Use of open-source and remotely-sensed data in the proposed project demonstrates the novelty of projects that do not include fieldwork, allowing for participation in oceanography by traditionally untapped talent. Increasing participation will bring new ideas to this topic, allowing for innovative approaches to understanding the ocean?s role in the carbon cycle which will then improve predictions of future global climate.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
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