NSF Award
2023274
Approximately one quarter of carbon emissions each year is taken up by the worlds’ oceans, which play a critical role in the global carbon cycle. As the oceans continue to respond to climate change, it is important to understand the carbon cycle and how it will change as well. In the surface waters of the ocean, phytoplankton take up carbon through photosynthesis, and a small fraction of this material then sinks to the deeper ocean in a process referred to as the “biological pump.” Current estimates of the global biological pump are similar in size to the amount of global carbon emissions, but uncertainties in these estimates are very large. This project will focus on understanding the role that marine phytoplankton in the North Atlantic Ocean play in the carbon cycle. The project will employ coordinated use of state-of-the-art, remote observational tools, namely biogeochemical profiling floats and ocean color observations from satellites. New techniques will be developed to maximize the information that can be glean from these observations and constrain biological carbon fluxes out of the sunlit upper ocean and through its deeper interior layers over basin-wide, seasonal, and annual scales. Finally, the performance of existing, satellite-based models of these biological fluxes will be evaluated in comparison with analogous estimates made from biogeochemical profiling float data, which can help to fill in satellite observing gaps below the surface and during periods of heavy cloud cover. The proposed effort will provide training and mentorship to a graduate student and a postdoctoral researcher. Outreach will be conducted through the 2021 Education And Research: Testing Hypotheses (EARTH) Workshop: A successful, ~15-year collaborative effort between MBARI and the Monterey Bay Aquarium to assist educators with incorporating ocean science information and real-time data into the classroom. To enhance diversity and inclusion in ocean science, a first-generation college student will be selected to participate in the 2021 MBARI Summer Intern Program. <br/><br/>Persistent and spatially-distributed in situ observations are needed to develop, and continuously train, more accurate models and remote-sensing algorithms to reduce the uncertainty (currently >100%) in estimates of the biological pump magnitude. The goals of the proposed effort are to develop, implement, and compare robust methods for quantifying biological carbon sequestration by leveraging the complementary information provided by bio-optical and chemical sensors on profiling floats deployed in the North Atlantic Ocean. This project will dovetail with several larger observational programs (EXPORTS, PACE, and pending Global Biogeochemical Argo) and leverage committed NOAA and NASA funding to deploy four biogeochemical profiling floats. Results from the analysis of float data will also be compared with estimates derived from satellite observations to assess the influences of 1) subpolar spring bloom timing and magnitude; and 2) more efficient subtropical carbon export processes, on the amount of carbon annually sequestered by the biological pump. Evaluating carbon production, recycling, and export from different perspectives (e.g., chemical, optical, and remote sensing), will capitalize on the strengths of different sensors and platforms using a combination of standard and novel methods. Quality-control of the data from ~300 existing and four newly deployed profiling floats in the North Atlantic will result in a valuable resource for other investigators. Data handling and processing tools developed during this project will be made publicly available to reduce barriers to entry for other scientists and students interested in analyzing large volumes of BGC float and ocean color data.<br/><br/>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.
