A sulfur hexafluoride section in the North Pacific Ocean: Application of a dual tracer approach

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The North Pacific Ocean plays an important role in the uptake and storage of anthropogenic CO2. According to past research using chemical tracers, the North Pacific Ocean has been identified as a critical region where climate variability is causing changes in oceanic CO2 ventilation rates. Chemical tracers used in previous research, have resulted in data describing only a portion of CO2 transit timescales and were strongly affected by oceanic mixing. To enhance the use of tracer results, two ocean chemists from the University of Washington plan to utilize dual chemical tracers to provide more accurate determinations of thermocline ventilation, oxygen utilization, and anthropogenic CO2 uptake rates. By combining the use of chlorofluorocarbons (CFCs) and sulfur hexafluoride (SF6) as the tracers in a dual tracer approach, the results from this research would refine CO2 transit time distributions (TTD) and implicitly account for ocean mixing while calculating more accurate CO2 ventilation rates. The estimations of these acidification and ventilation rates are of significance to the understanding of the implications of global climate change including anthropogenic CO2 uptake by the oceans, ocean acidification, biological export rates, and decadal climate variability.As regards broader impacts, one graduate student would be supported and trained as part of this project. One undergraduate student would participate in the cruise, learn how to measure trace gases, and the data would provide the basis for his/her undergraduate research project.