The North Pacific accounts for ~25% of the global ocean’s uptake of carbon dioxide (CO2) from the atmosphere. However, the relative importance of the biological pump vs. physical circulation in driving ocean uptake of CO2 remains poorly understood.
In a recent study, Palevsky and Quay (2017) used geochemical measurements collected on sixteen container ship transects between Hong Kong and Long Beach, CA to evaluate the drivers of CO2 uptake across 8,000 kilometers in the North Pacific basin over the full annual cycle. In the eastern North Pacific, biologically-driven export of organic carbon below the winter ventilation depth fully offsets the uptake of CO2 from the atmosphere. However, in the Kuroshio region of the western North Pacific, which has a deep winter mixed layer, the majority of the organic carbon exported during the productive summer season is subsequently respired and ventilated back to the atmosphere in winter. Subsequently, biologically-driven export offsets only a small fraction of the CO2 uptake by the ocean and, instead, physical transport is the dominant process removing inorganic carbon from the region.
We further show that that mechanistic coupling between biological carbon export and ocean uptake of CO2 from the atmosphere is sensitive to the seasonal timing of biological export and ventilation, as well as the magnitude of export. Future studies therefore need to measure biological carbon export and ventilation throughout the full annual cycle in order to better understand controls on regional variations in ocean CO2 uptake rates and future changes in these rates.

Data from 16 shipboard transects across the North Pacific revealed a basin-wide gradient between the Kuroshio and Eastern regions in the relative roles of biological vs. physical processes in removing dissolved inorganic carbon from the surface ocean.
Authors:
Hilary I. Palevsky (Woods Hole Oceanographic Institution)
Paul D. Quay (University of Washington)

Christiana Ade is a first-year PhD student at North Carolina State University in the Marine, Earth and Atmospheric Sciences Department. She researches wetlands and coastal environments using satellite remote sensing and field measurements. Her research includes water quality mapping, establishing new environmental indicators, and determining satellite resolution requirements for adequately monitoring wetlands.
Henry Houskeeper
Suhey Ortiz Rosa is a PhD student conducting research with Dr. Roy Armstrong in Bio-Optical Oceanography at the Department of Marine Sciences at the University of Puerto Rico- Mayagüez (UPRM). In 2005, she completed a B.S. in Coastal Marine Biology at the University of Puerto Rico- Humacao, and in 2010, a MS in Chemical Oceanography at UPRM. Suhey’s work focuses on the biogeochemistry of coastal waters and coral reefs, validating algorithms from satellite imagery of complex optical waters, remote sensing, and GIS. Previously, she worked on CDOM characterization with PARAFAC, mapping marine species distribution with the GAP-Analysis Project of Puerto Rico and later with watershed analysis of sedimentation processes on coral reefs.
Sara Rivero-Calle is a postdoctoral researcher at the Levine Lab in the University of Southern California interested in projects that involve large datasets, combining remote sensing and in situ data to answer large-scale ecological questions. She first learned about satellite remote sensing during her MS program at the University of Puerto Rico working on mesophotic reef sponge ecology using Autonomous Underwater Vehicles. She earned a PhD from Johns Hopkins University, where she used the Continuous Plankton Recorder survey to study long-term changes in North Atlantic phytoplankton communities. Currently, Sara is conducting postdoctoral research on fine-scale variability and patchiness, combining remote sensing, float, and HPLC data with numerical models.
Sarah Schlunegger is a PhD Student in the Program of Atmospheric and Oceanic Sciences, advised by Prof. Jorge Sarmiento. Sarah uses Earth System Models to predict the timing, sequence and inter-dependence of emerging anthropogenic signals in the ocean, with a focus on the ocean’s acquisition of anthropogenic carbon and heat. The ocean provides a climate service by absorbing the atmosphere’s excess carbon and heat but at a cost, namely acidification and warming, which deteriorate marine habitats. Sarah’s primary research goal is to identify when and where changes in these heat/carbon sinks and their resulting impacts will be detectable in the ocean.









