McKinley, Galen: Columbia University / Lamont Doherty Earth Observatory (Project Lead)
Project Funding:
2011 - 2016
NRA: 2009 NASA: The Science of Terra and Aqua
Funded by NASA
Abstract:
Introduction of Problem and Rationale: The ocean has taken up 48% of the anthropogencially emitted CO2 since preindustrial times (Sabine et al. 2004). A detailed, mechanistic understanding of this uptake of carbon is required in order for us to be able to both monitor changes in the ocean carbon sink, and to predict its future change. The sinking of biogenic particles from the surface ocean and their remineralization at depth constitutes the â€biological pump†portion of ocean carbon sink and is determined, in large part, by the phytoplankton community size structure of the surface ocean (Boyd and Trull, 2007; Boyd and Newton, 1995, 1999; Guidi et al. 2009). These authors, and others (Dunne et al. 2005, Lutz et al. 2007), suggest that satellite-retrieved chlorophyll concentration and primary production are not enough to predict changes in the removal of organic material from surface waters and its fate at depth, yet these have been the only satellite-derived variables available to us until very recently. We propose that additional progress can be made by taking advantage of recent satellite-derived retrievals of phytoplankton size distribution (percent microplankton, Sfm) that have been shown to have high fidelity for the global ocean (Mouw and Yoder, 2010a).
Numerical models of the global ocean ecosystems have typically had a fixed number of phytoplankton species and a few pathways for production of particulate detritus that then sinks and remineralizes at fixed rates. A novel self-organizing ecosystem model (Follows et al. 2007), the â€Darwin modelâ€, has many tens to hundreds of phytoplankton species and so can capture more accurately the evolving distribution of the phytoplankton community. With the improvements to its export and remineralization parameterizations that we will make, this model will be an ideal testbed for assessing the importance of phytoplankton community size structure to the biological pump.
Brief Summary of work: In this project, we will (1) use newly-available satellite retrievals of phytoplankton community size structure to refine and connect two data-based empirical algorithm for the surface export of biogenic particles (Dunne et al., 2005) and their remineralization at depth (Lutz et al., 2007), (2) integrate into the Darwin model these relationships, along with other improvements to the export paramaterization, and (3) use the improved Darwin model to understand connections between phytoplankton size structure and ocean carbon uptake and storage. We will address the following science questions:
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Publications:
Gloege, L., McKinley, G. A., Mouw, C. B., Ciochetto, A. B. 2017. Global evaluation of particulate organic carbon flux parameterizations and implications for atmospheric pCO2. Global Biogeochemical Cycles. 31(7), 1192-1215. DOI: 10.1002/2016GB005535
Mouw, C. B., Barnett, A., McKinley, G. A., Gloege, L., Pilcher, D. 2016. Phytoplankton size impact on export flux in the global ocean. Global Biogeochemical Cycles. 30(10), 1542-1562. DOI: 10.1002/2015GB005355
More details may be found in the following project profile(s):
