MRI-R2: Development and Deployment of Automated Continuous Wave Quantum Cascade Laser Instruments For On-Site Monitoring of the Four Isotopomers of Nitrous Oxide

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。一氧化二氮（N2O）既是一种重要的温室气体（2009年的辐射强迫约为0.17 W/m2），也是对平流层臭氧层的催化破坏的重要贡献者。它在大气中的摩尔分数继续从工业化前的自然值约270 ppb上升到今天的约322 ppb。然而，这种第三多的长寿命温室气体的全球循环存在主要的不确定性。为了解决这些不确定性，研究人员建议开发和部署两种基于高频激光的自动化仪器，用于分析N2O的同位素物和同位素体。同位素比率将使用可调谐红外激光微分吸收光谱（TILDAS）与连续波（CW）量子级联（QC）激光器进行监测。这项技术非常适合长期部署在远程站点，因为仪器是完全自动化的，也可以通过互联网访问和控制。新仪器将监测四种氧化亚氮的同位素物。N2O摩尔分数的连续地表测量为通过逆模型研究分析全球预算提供了重要资源，但这些摩尔分数数据的利用已经达到了可提取信息的极限，并且留下了很大的不确定性。高频同位素体/同位素测量能力的发展将大大提高目前在科学理解和政策核查所需的空间和时间分辨率上区分对其预算的自然和人为贡献的能力。在其中一个AGAGE（先进全球大气气体实验）站（自1978年以来一直在现场测量微量气体，包括N2O）的部署将产生一组前所未有的数据，包括具有相同分子质量的同位素。同样，对主要氧化亚氮源的同位素特征进行现场高频测量，可能会对源动力学和同位素变异性产生新的见解。该项目将促进Aerodyne研究公司（美国小企业）和麻省理工学院（MIT）之间的合作，共同开发新一代同位素监测设备。研究生将积极参与发展，培养成为具有强大仪器背景的未来大气化学家。麻省理工学院的仪器将用于本科水平的课堂项目，以及本科和研究生的论文研究项目，也将向麻省理工学院以外的研究人员开放合作项目。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Nitrous oxide (N2O) is both a significant greenhouse gas (radiative forcing in 2009 is approximately 0.17 W/m2) and a large contributor to the catalytic destruction of the stratospheric ozone layer. Its mole fractions in the atmosphere continue to rise from a natural preindustrial value of about 270 parts per billion (ppb) to about 322 ppb today. However, there are major uncertainties in the global cycle of this third most abundant long-lived greenhouse gas. To address these uncertainties, the investigators propose the development and deployment of two automated high frequency laser-based instruments for analysis of the isotopologues and isotopomers of N2O. Isotopic ratios will be monitored using tunable infrared laser differential absorption spectroscopy (TILDAS) with continuous wave (CW) quantum cascade (QC) lasers. This technology is well suited for long-term deployment at remote sites as the instruments are fully automated and can also be accessed and controlled via the Internet. The new instruments will monitor four isotopologues/isotopomers of nitrous oxide. Continuous surface measurements of the mole fraction of N2O have provided an important resource in analysis of the global budget through inverse modeling studies, but the utilization of these mole fraction data has reached the limit of information that can be extracted and leaves large uncertainty remaining. The development of high-frequency isotopomer/isotopologue measurement capability will greatly enhance current ability to differentiate between the natural and anthropogenic contributions to its budget at the spatial and temporal resolution needed for scientific understanding and policy verification. The deployment at one of the AGAGE (Advanced Global Atmospheric Gases Experiment) stations (that has been measuring trace gases including N2O on site since 1978) will produce an unprecedented set of data including isotopomers with identical molecular mass. Similarly, the in situ high-frequency measurements at field sites of the isotopic signatures of the dominant nitrous oxide sources could potentially yield new insights into source dynamics and isotopic variability.The project will facilitate the collaboration between Aerodyne Research, Inc. (U.S. small business) and Massachusetts Institute of Technology (MIT) for the development of a new generation of isotope monitoring equipment. Graduate students will actively participate in the development and be trained as future atmospheric chemists with strong instrumental background. The MIT instrument will be used for undergraduate level class projects as well as for undergraduate and graduate thesis research projects, and will also be open to collaborative projects with researchers outside MIT.