Measurements of Stable Isotope Compositions of Greenhouse Gases in the Stratosphere & Upper Troposphere: Applications to Stratospheric Chemistry, Transport & Global Biogeoc

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This project is focused on studying the isotopic composition of chemically and radiatively important trace gases such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) in the stratosphere and upper troposphere. Continuous-flow isotope ratio mass spectrometry will be used to analyze a subset of whole air samples obtained from the NASA ER-2 high-altitude aircraft. The results will be interpreted in terms of (a) establishing a data base of the global-scale variations in stratospheric isotope compositions and (b) constraining isotope fractionation mechanisms in the stratosphere. Further objectives are to determine the feasibility of using isotopic observations to (a) quantify vertical and horizontal transport in the stratosphere, (b) distinguish chemical ozone loss from ozone changes due to transport alone, (c) improve estimates of stratosphere-troposphere exchange, and (d) derive improved estimates of the influence of stratospheric fractionation processes on the isotopic compositions of tropospheric N2O, CO2, and, by inference, O2.