Ultrasonic Detector for Carbon Dioxide

70042 The quantification of sources and sinks of atmospheric carbon dioxide would be greatly facilitated by the development of a new detector for this important greenhouse gas. In particular a lightweight CO2 sonde, similar to the widely used ozonesonde, could be used to estimate landscape-scale fluxes of CO2 characteristic of ¿ 100 km2 from vertical profiles through the convective boundary layer. This project will develop a new CO2 detector based on the measurement of the speed of sound in air. In addition to its applicability to fixed ground-based and tower-based measurements, the new instrument will be sufficiently lightweight and inexpensive to be used as a release sonde. The ultrasonic detector will be highly selective for CO2 and have a precision of one part in 3000 or better, corresponding to a detection limit of 0.1 ppmv. In Phase I, the ultrasonic detector will be designed, constructed, and optimized for the sensitive detection of CO2 in air. The new instrument will be evaluated with respect to analytical figures of merit, including precision, accuracy, limit of detection, linear range and selectivity. Commercial Applications and Other Benefits as described by the awardee: The CO2 ultrasonic detector should have commercial applicability for a wide range of applications in addition to carbon cycling studies. These include the analysis of atmospheric gases for water vapor and compressed gas analysis for the semiconductor and natural gas industries.