BIOCOMPLEXITY: High-Precision 13CO2/12CO2 Ratio Measurements Using an Optical Fiber Based Difference Frequency Generation Laser Source

该项目需要开发、测试、验证和部署基于中红外激光的气体传感器系统，用于连续原位测量大气二氧化碳的同位素组成(13CO2/12CO2比率)，精度等于或优于每密耳0.1。来自国家大气研究中心、莱斯大学和科罗拉多大学的一个科学团队将利用光纤技术的最新发展、差频产生(DFG)的最新进展以及在碳循环研究方面的多年经验。拟议的DFG仪器将使用在室温下工作的商用电信激光器。这种激光光源在实现高测量精度方面比更传统的激光系统具有显著的优势。该仪器将用于获得13CO2/12CO2比率的高精度大气测量--这一测量目前是通过烧瓶样品网络和质谱分析完成的。这些数据对于理解陆地和海洋碳汇是至关重要的，这需要了解区域和当地的二氧化碳源和汇过程的分布、贡献和演化。需要高精度的连续测量以提供广泛的时间和空间覆盖，尽管同位素精度低于烧瓶方法(每密耳0.012)。目前还没有一种坚固耐用的现场可部署仪器，能够以每密耳0.1或更高的精度连续测量13CO2/12CO2，并具有可核查的准确性。这项工作的第一阶段将侧重于广泛的实验室测试，以确定和实施最佳实验条件以及数据采集和检索程序。下一阶段将重点放在现场测量的最佳包装上，随后将与科罗拉多大学尼沃特岭天文台现场进行的最先进的烧瓶样品/质谱学测量进行广泛的并排比较。将在地面和科罗拉多大学塔楼设施上进行共同定位的测量。新的连续测量将为Niwot Ridge站点的长期数据库提供基础，并为进一步将这些新测量扩展到其他场地和平台提供必要的经验。该项目在碳循环研究领域具有潜在的广泛影响。此外，这种新的仪器和相关的新方法可以适用于其他需要超高测量精度的新研究问题。此外，与研究生和本科生、高中生和教师一起的多方面教育计划将把对这种新的激光和光纤技术的理解和使用转移到更广泛的科学界。将向学生介绍1)光纤技术及其应用的潜力；2)碳循环的概述；3)高精度二氧化碳同位素比率测量的挑战和信息含量。

This project entails the development, test, validation, and deployment of a mid-infrared laser based gas sensor system for continuous in-situ measurements of the isotopic composition of atmospheric carbon dioxide (13CO2/12CO2 ratio) with a precision equal to or better than 0.1 per mil. A science team from the National Center for Atmospheric Research, Rice University, and the University of Colorado will utilize the latest developments in optical fiber technology, recent advances in difference frequency generation (DFG), and multi-year experience in carbon cycle research. The proposed DFG instrument will employ commercially available telecommunication lasers which operate at room temperature. Such a laser source presents significant advantages over more traditional laser systems for achieving high measurement precision.The instrument will be used to acquire high precision atmospheric measurements of 13CO2/12CO2 ratios - a measurement currently accomplished by a network of flask samples followed by mass spectrometric analysis. These data are crucial for understanding terrestrial and oceanic carbon sinks which requires an understanding of the distribution, contribution, and evolution of regional and local CO2 source and sink processes. High precision continuous measurements are needed to provide broad temporal and spatial coverage, even though the isotopic precision is inferior to the flask method (0.012 per mil) At present there does not exist a robust field-deployable instrument capable of continuous 13CO2/12CO2 measurements with a precision of 0.1 per mil or better with verifiable accuracy.The first phase of this effort will focus on extensive laboratory testing to identify and implement optimal experimental conditions and data acquisition and retrieval routines. The next phase will focus on optimal packaging for field measurements, and this will be followed by an extensive set of side-by-side comparisons with state-of-the-art flask sample/mass spectrometric measurements carried out in the field at the University of Colorado's Niwot Ridge Observatory site. Co-located measurements will be carried out on both the ground and the University of Colorado tower facility. The new continuous measurements will provide the foundation for a long-term database from the Niwot Ridge site as well as the necessary experience to further extend these new measurements to other venues and platforms. This project has potential broad impacts in the area of carbon cycle research. In addition, the new instrument and associated new approaches can be adapted to other new research problems requiring ultra high measurement precision. Moreover, a multifaceted educational program with graduate and undergraduate students, high school students and teachers, will transfer the understanding and use of this new laser and fiber optic technology to a broader scientific community. The students will be introduced to 1) the potential of optical fiber technologies and its applications; 2) an overview of the carbon cycle; and 3) the challenges of, and information content offered by, high precision isotopic ratio measurements of CO2.