CAREER: Measurement and Modeling of Land-Atmosphere Isotopic Carbon Dioxide (CO2) Exchange in the Upper Midwest, United States

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The goal of this project is an improved understanding of the biophysical processes and discrimination mechanisms controlling the exchange of carbon dioxide (both 13C and 12C CO2) between the land and atmosphere at the ecosystem, landscape, and regional scales. It will focus on improved methods for measuring and modeling concentrations of trace species and fluxes in and out of the atmosphere. The approach utilizes fast tunable diode laser (TDL) measurement of isotopomer mixing ratios in combination with the eddy covariance approach for isotopic flux measurements in a heterogeneous landscape from a tall tower. The objectives are to: 1) Develop and improve micrometeorological and boundary layer methods for measuring isotopic carbon dioxide (CO2) fluxes; 2) Quantify isotopic fluxes and biophysical parameters to help understand 13CO2 discrimination mechanisms; 3) Determine the extent, rate of change, and controls on isotopic disequilibrium within a heterogeneous region in the upper Midwest, United States; and 4) Combine measurements and models to constrain key discrimination parameters at the ecosystem, landscape, and regional scales.Undergraduate training activities will be provided in micrometeorological theory and techniques, stable isotope theory and techniques, data acquisition methods, and modeling. An intermediate undergraduate course on Land-Atmosphere Interactions will be developed and will include an intensive 2-week field component. Broader impacts also include the development of techniques for studying the impact of climate variation and land management on atmospheric CO2, assessment of the carbon sink/source potential of regions dominated by land use change, and outreach efforts including collaboration with Minnesota Public Radio.