Dual Laser Isotopic Flux Monitor for Carbon Dioxide and Water Vapor

The increase of carbon dioxide (CO2) in the Earth¿s atmosphere is the most important driver of global warming. In order to predict future carbon dioxide concentrations under various mitigation strategies, a much better quantitative understanding of the sources and sinks of atmospheric carbon dioxide is required. Studying the ratios of the stable isotopes of CO2 has long been recognized as a tool for identifying sources and sinks of atmospheric CO2. Because of the coupling of the water and carbon dioxide cycles, measurements of isotopic water vapor also are required to quantify the carbon cycle. This project will develop an advanced laser-based instrument for the simultaneous real-time measurement of isotopologues of CO2 and H2O. This instrument will be suitable for field-measurement of isotopic fluxes by eddy covariance, allowing the determination of wide area emission and deposition of CO2, and allowing the partition between plant photosynthesis and respiration fluxes. In Phase I, a CW-QC laser was used to demonstrate outstanding precision (0.03¿) for the measurement of the target CO2 isotopologues with a cryogen free system. In Phase II, a second CW-QC laser will be obtained for the measurement of H2O isotopologues (H216O, H218O, HD16O). The combined prototype instrument and its calibration system will be designed, constructed, and tested. Commercial Applications and other Benefits as described by the awardee: The primary market for this instrument will be atmospheric, ecological, and environmental research groups at universities and national laboratories. The instrument has the potential to benefit human health and well being by improving our understanding of the sources and sinks of atmospheric CO2.