Phytoplankton to the Ocean's Biological Pump: How Far Have We Come & How Far Do We Have To Go?

Dave Siegel, UC Santa Barbara, davey@icess.ucsb.edu (Presenter)

Satellite ocean color observations have dramatically changed how we observe and understand global ocean ecological processes. These space-based observations of surface layer chlorophyll concentrations have enabled investigators to elucidate intense spring plankton blooms and their decay as well decadal-scale trends. Satellite ocean color observations also illustrate the rich spatial variability in ocean ecological processes from 1-km coastal jets and squirts to 100-km rings and eddies to 10,000-km variations among the ocean basins. These advances have occurred due to the availability of high quality, synoptic spatial and persistent coverage that NASA’s ocean color satellite sensors have provided.
In spite of these advancements, satellite-based assessments of the ocean carbon cycle have lagged behind. This is particularly evident in the remote quantification of the ocean’s biological pump; the set of biotic and biogeochemical processes that export fixed carbon from the surface ocean and sequester it to depth where it removed from contact with the atmosphere on time scales from months to millennia. The remote characterization of the biological pump requires novel satellite data products far beyond surface layer chlorophyll concentrations available from operational satellite systems.
In this talk I will sketch out a path towards constraining the sequestration of upper ocean carbon stocks via assessing the export and fate of upper ocean net primary production from satellite observations. The approach requires understanding and measuring the changes in size- and functional type- fractionated phytoplankton carbon stocks and fluxes and their roles in ocean food webs. Achieving this goal will require both improvements in satellite data products, through advancing active and passive space-based observational capabilities, and conducting intensive field campaigns, aimed at developing a predictive understanding of carbon cycling processes from remotely sensed observables. Steps towards the implementation of this vision are underway, such as the upcoming PACE mission, ocean carbon retrievals using the CALIOP lidar and the EXPORTS Science Plan, and will be discussed.

Presentation: 2015_Apr21_AM_Siegel_26.pdf (9919k)

Presentation Type:  Plenary Talk

Session:  Theme 3: Future research direction and priorities: perspectives relevant to the next decadal survey

Presentation Time:  Tue 9:20 AM  (20 minutes)