Assessment of Ocean Carbon Export and Sequestration From Satellite Data: New Approaches and a Plan for the Future

The biological carbon pump is thought to export ~10 Pg C each year from the surface ocean to depth largely in the form of settling organic particles and this export and the time scale of its sequestration at depth are important components of the global carbon cycle. However little is known about how these fluxes will change in a changing climate. Assessments of the global export flux have either been through the extrapolation of point measurements to global scales or the results of ocean system model experiments. Satellites resolve relevant space and time scales providing guidance to the empirical extrapolation problem, but they do not quantify directly carbon export. Here, we present a mechanistic approach for assessing global carbon export linking satellite data with food web models. The synthesis does an excellent job reproducing regional export flux observations and reproduces the basic patterns of export spatially and seasonally. Further comparison with available long-term, deep sea sediment trap observations results in remineralization length scales for sinking organic carbon consistent with previous summaries. This approach provides many insights into future research on carbon export and sequestration and ecosystem dynamics. The science plan for a NASA field campaign on assessing the export and fates of net primary production, the EXport Processes in the Ocean from RemoTe Sensing (EXPORTS), is presented as a step towards that future.