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

该项目的目标是在生态系统、景观和区域尺度上提高对陆地和大气之间二氧化碳（13C和12C CO2）交换的生物物理过程和区分机制的理解。它将侧重于改进测量和模拟大气内外痕量物种浓度和通量的方法。该方法利用快速可调谐二极管激光（TDL）测量同位素混合比，结合涡流相关方差方法在高塔非均质景观中测量同位素通量。目标是：1)发展和改进测量同位素二氧化碳通量的微气象和边界层方法；2)量化同位素通量和生物物理参数，帮助了解13CO2的识别机制；3)确定美国中西部上部非均质区域内同位素不平衡的程度、变化率和控制；4)结合测量和模型，在生态系统、景观和区域尺度上约束关键判别参数。提供微气象理论与技术、稳定同位素理论与技术、数据采集方法和建模等方面的本科生培训活动。将开设一门关于陆地-大气相互作用的中级本科课程，其中包括为期两周的密集实地课程。更广泛的影响还包括开发研究气候变化和土地管理对大气二氧化碳影响的技术，评估以土地利用变化为主的地区的碳汇/源潜力，以及开展外联工作，包括与明尼苏达州公共广播电台合作。

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.