Lightweight, High-Precision Instrument for Balloon Sonde CO2 Measurements

More accurate determination of CO2 in the atmosphere is required to reliably quantify the sources and sinks of carbon in the environment. Current CO2 analytical instrumentation is relatively large and heavy, and requires significant amounts of electrical power to operate. As a result, in situ CO2 measurements presently can be recorded only on weight-bearing vehicles (e.g., aircraft) that fly infrequently; as a consequence, measurements with high spatial or temporal resolution cannot be reported. This project will develop, test, and deploy inexpensive, low-power CO2 sensors (weight < 100 grams) that will be capable of reporting CO2 with an uncertainty of less than 1 ppmv in the troposphere and tropopause. These instruments, which will be based on absorption spectroscopy techniques, will be designed to report CO2 measurements while onboard balloon sondes over extended periods. Phase I designed, built, and tested a novel compact CO2 sensor based on absorption spectroscopy. The instrument demonstrated a measurement precision of 1 ppmv over a range of concentrations typical in ambient air and in industrial processes. Phase II will develop, test, and deploy several CO2 sensors on board balloons for measurements in the troposphere and tropopause at a DOE Atmospheric Radiation Measurement site. The Phase II instrument will weigh about 100 grams and operate on a lightweight battery. Commercial Applications and Other Benefits as described by the awardee: The new CO2 sensor should significantly enhance studies of global warming, and facilitate controlled multi-year studies and comparisons between geographically distant field sites. The instruments will thus help quantify in detail the global carbon cycle on local and large spatial scales and enable atmospheric chemists to generate reliable models of climate change and carbon sequestration. Commercial applications include atmospheric studies of carbon sources and sinks, industrial process control (chemical and petrochemical refineries), and pollution detection.