Award: OPP-1643386

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: 09/16/2020 Submitted by: Michael Dinniman