Expendable Probes for Carbon Dioxide

78574S A wide range of practical instruments is needed for monitoring carbon dioxide concentrations of the land, air, and sea. Moderate accuracy and precision of order 1 ppm (dry mole fraction) will suffice. Expense, weight, size, and electrical power must be kept low to make the instrumentation applicable to a large number (~10,000) of one-way deployments per year. Accessible platforms include weather balloons, miniature buoys for probing just beneath the ocean's surface, and passive cavities maintained on or within the soils of terrestrial ecosystems. This project will design, build, and deploy expendable solid state probes to quantify the natural CO2 concentrations of the air, land and sea. Three demonstrations will be deployed to monitor CO2 concentrations of miniature hydrophobic cavities in mechanical contact with and surrounded by: (1) the free atmosphere, (2) the soil of a terrestrial ecosystem, and (3) the surface layer of the ocean. Phase I will design and evaluate prototypes of two kinds of NonDispersive InfraRed (NDIR) analyzers, photo-electronic and photo-acoustic. The most promising one will be built into a functioning probe, calibrated for wide ranging changes in ambient conditions, and used to monitor the free atmosphere. A microprocessor will be designed to implement the calibration and to enable remote communications. Hydrophobic cavities will be used to quantify temporal resolution and to verify performance in underground and underwater deployments. Commercial Applications and Other Benefits as described by the awardee: The expendable probes should generate a market on the of order 10,000 units per year. 75,000 weather balloons are launched worldwide each year (air), and there are approximately 10,000 spatial elements of the ocean surface that should be monitored seasonally. In addition, numerous deployments onto and under the ground of terrestrial ecosystems would benefit from the development of expendable solid state probes. Observations from the probes should provide information on carbon sequestration by the global biosphere and its response to climate change.