A Novel Faraday Filter-based Spectrometer for Studying the Sodium Airglow and Measuring the Atomic Oxygen Mixing Ratio in the Upper Mesosphere

一种新型法拉第滤光片光谱仪，用于研究钠气辉并测量上层中间层的原子氧混合比

• 批准号: 0804295
• 负责人: Chiao-Yao She
• 金额: $ 10万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-06-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0804295&HistoricalAwards=false
• 关键词: Novel; Faraday; Filter; based; Spectrometer

This project will develop and deploy a new optical instrument, a compact spectrometer, that will enable new measurements of the mesospheric sodium nightglow. One of the primary aims is to determine the ratio of two sodium emission lines, the D2 and D1. Early studies predicted that the D2/D1 ratio might differ from its quantum statistical value of 2 due to chemical interactions. However, measurements taken three decades ago using a Fabry-Perot instrument reported a value of 1.98±0.1; since then, 2 has taken to be the correct value without further investigation. Recently, T. G. Slanger, J. M. C. Plane and others have searched through sky spectra from Keck telescopes taken over 8 years, and deduced that depending on atmospheric conditions, the value NaRD = I(D2)/I(D1) lies between 1.2 and 1.8. A clear seasonal dependence of this ratio, with higher values in equinox and lower values in solstice, was noted as well. They proposed a modified Chapman mechanism which suggests competing pathways of NaO+O reactions produce Na nightglow emission. Substantiated by laboratory experiments, they concluded that the ratio NaRD is a reliable proxy for the measurement of the [O]/[O2] ratio. Since atomic oxygen is probably the most important species in determining the chemistry and dynamics of the mesosphere and lower thermosphere (MLT), even an indirect real-time determination of [O]/[O2] could greatly advance our understanding of the MLT energy balance, especially since there is no direct ground-based method for observing the atomic oxygen concentration, [O]. Through this project, a novel, compact spectrometer, based on a pair of modified Na vapor Faraday filters, will be designed to measure Na nightglow and to determine NaRD. In addition to NaRD, the method can also determine the pathway fractions of the two possible reactions in the modified Chapman process. The NaRD spectrometer will be deployed at the Colorado State University lidar site for intitial testing and calibration. The project involves a research scientist as Co-PI and a graduate student for his Ph.D thesis. The research would lead to the development of an inexpensive compact spectrometer that could be used at other observatories with a simple sodium lidar. The project will contribute to studies of atomic oxygen in the mesopause region as more data are gathered from various sites in the future. Such measurements will improve the understanding of the aeronomy of airglow processes, most of which involve interactions with O.

该项目将部署一种新的光学仪器，一种紧凑的光谱仪，一个一个One One One One ONS，以确定D2和D1的两个钠排放线。使用Fabry-Perrot仪器的化学相互作用，从那时Nard = I（D2）/I（D1）在1.2和1.8之间。通过实验室实验，他们得出的结论是，在确定中脊髓和热球（MLT）的化学和动力学方面，对[o]的最重要物种的测量值是可靠的，即使是间接实时确定[O] /[O2]可以大大提高我们对观察原子氧浓度的MLT能量平衡的理解，[O]，这是一对基于一对修改的NA Vapor Faraday过滤器的小说。 Nard。他的博士学位论文的研究生。提高对气球过程气流过程的理解，大多数涉及与O的相互作用。