Development of a Micro-Rosette Sensor for Total Dissolved Inorganic Carbon Measurement from Autonomous Lagrangian Ocean Profilers

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Arrays of profiling floats provide the potential for orders-of-magnitude improvement in ocean observing, relative to ships. This fact has already been realized by physical oceanographers studying the ocean heat budget and large-scale mixing processes and is now gaining momentum in the ocean biogeochemistry and ecological modeling communities. Attempts to add off-the-shelf sensors for the CO2 system to profiling floats has thus far been ineffectual because these devices were not built with the express intention of operating on profilers, and because the sensors available at present are limited to pCO2 measurements which require long dwelling times at depth intervals for equilibration due to slow response times as pCO2 is highly sensitive to temperature and pressure and cannot be easily measured ex-situ. Consequently, there is currently no technology available for meaningful observations of the inorganic carbon system from profiling floats. The micro-rosette approach outlined in this proposal will allow, for the first time, profiles of dissolved inorganic carbon from profiling floats.The PI's request funding to build and test a new concept: a "micro-rosette" to be deployed on an ARGO-type profiling float. The micro-rosette is a device intended to operate specifically on board a profiling float, capturing discrete seawater samples during float ascent and storing them for subsequent chemical analysis. The application that we focus on here is the measurement of total dissolved inorganic carbon, CT. This will result in the first autonomous, Lagrangian vertical profiles of CT. Realizing a working prototype micro-rosette involves an engineering component in order to develop a low power carousel-type device in addition to a chemistry componentresponsible for modification and fine-tuning of a proven flow injection analysis method. A successful project will result in the first autonomous, Lagrangian vertical profiles of CT in the upper 2000 m, marking a major step in development of a new generation of tools necessary to better understand annual cycles of carbon in the ocean in addition providing direct observations of ocean acidification over large areas of the ocean.This project supports an increase in the level of collaboration between researchers in the US, Ireland, and Northern Ireland under the US/Ireland R&D Partnership Program. Each of the three partners will receive funding exclusively from their respective national science funding agencies. The effort is multi-disciplinary, and brings together expertise in ocean biogeochemistry (Martz, US), ocean physics (Ward, Ireland) and microfluidics engineering (Maguire and McLaughlin, Northern Ireland).Broader Impacts: The identified broader impacts included improving the quantity of data for evaluating present and future changes in the ocean inorganic carbon cycle and the great potential for application to other analytes. The collaboration between researchers in the US, Ireland, and Northern Ireland under the US/Ireland R&D Partnership Program must also be considered a broader impact. Each of the three partners will receive funding exclusively from their respective national science funding agencies. The effort is multi?disciplinary, and brings together expertise in ocean biogeochemistry (Martz, US), ocean physics (Ward, IE) and microfluidics engineering (Maguire and McLaughlin, NI). The US and Ireland portions includes support for a full time graduate student, the Northern Ireland portion will support a research associate.