Line Shape Parameters in Support of Remote Sensing of Earth's and Planetary Atmospheres

支持地球和行星大气遥感的线形参数

• 批准号: 1156862
• 负责人: Robert Gamache
• 金额: $ 43.42万
• 依托单位: University of Massachusetts Lowell
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1156862&HistoricalAwards=false
• 关键词: Line; Shape; Parameters; Support; Remote

This project involves development of a theoretical model to calculate pressure-broadened half-widths and pressure-induced line shifts and their temperature dependences for gases in the terrestrial and planetary atmospheres that meets the needs of the remote sensing community. The half-width remains the major source of error in the spectral parameters used for reducing remote sensing data and in line-by-line models used to calculate radiative forcing from greenhouse gases. Because data are needed for many thousands of ro-vibrational transitions of many different gases a computationally efficient theoretical model, based on physics, is desired that can correctly determine the line shape parameters. The semi-classical Complex Robert-Bonamy formalism is the basis of the theoretical approach. For results to be good for all transitions, not only strong lines, the intermolecular potentials must be expanded to very high order and the molecular dynamics must use Hamilton's equations. For transitions in the near infrared and visible spectral regions better wavefunctions and energies are needed, since the classic effective Hamiltonian determination breaks down. The use of ab initio energies and wavefunctions in the determination of the reduced matrix elements is being explored as a means to remedy the problem. The vibrational state, rotational state, and temperature dependence of the collision-induced parameters are being investigated. Because of the improvement in space borne spectrometers, line shape models need to be improved. While the Voigt model forms the basis for line shape, corrections for Dicke narrowing and speed dependence, and their correlation, must be and are being considered in this work.The resulting data will provide greatly improved line shape parameters and their temperature dependence, aiding researchers doing concentration and temperature profile retrievals and radiative transfer studies of the heat balance of Earth and other planets by reducing the uncertainty of the half-widths and other line shape parameters used in their models. This work will improve confidence in spectroscopic remote sensing results and allow a better determination of the radiative forcing of greenhouse gases. The improvement in understanding the energy balance of the Earth will help make more informed policy decisions. The data will be distributed via the HITRAN, HITEMP, GEISA, and IUPAC (for water vapor) databases and the principal investigator's web site. A postdoctoral scholar and several undergraduate students will work on this project, learning skills that they would not get in a classroom setting. An ongoing collaboration with a local high school allows undergraduate students to routinely visit the school to talk about their work with the aim of creating interest in science among the high schoolers.

该项目涉及开发一个理论模型，以计算地球和行星大气中气体的压力加宽半宽和压力引起的谱线偏移及其与温度的关系，以满足遥感界的需要。半宽度仍然是用于减少遥感数据的光谱参数和用于计算温室气体辐射强迫的逐线模型的主要误差来源。由于需要许多不同气体的数千个振转跃迁的数据，因此需要基于物理学的计算有效的理论模型，该模型可以正确地确定线形状参数。半经典的复Robert-Bonamy形式主义是理论方法的基础。为了使结果对所有跃迁都好，不仅是强谱线，分子间势必须扩展到非常高阶，分子动力学必须使用汉密尔顿方程。对于在近红外和可见光谱区的跃迁，需要更好的波函数和能量，因为经典的有效哈密顿量的确定打破了。使用从头算能量和波函数在确定减少矩阵元素正在探索作为一种手段来解决这个问题。碰撞诱导参数的振动态，转动态和温度依赖性正在研究中。由于星载光谱仪性能的提高，谱线形状模型需要改进。虽然Voigt模型形成了线形的基础，但在这项工作中必须并且正在考虑对迪凯窄化和速度依赖性的校正以及它们的相关性。由此产生的数据将提供大大改进的线形参数及其温度依赖性，通过减少不确定性，帮助研究人员对地球和其他行星的热平衡进行浓度和温度剖面反演以及辐射传输研究半宽度和其他线形参数的模型中使用。这项工作将提高光谱遥感结果的可信度，并能更好地确定温室气体的辐射强迫。对地球能量平衡的进一步了解将有助于作出更明智的决策。这些数据将通过HITRAN、HITEMP、GEISA和IUPAC（用于水蒸气）数据库以及主要研究者的网站发布。一名博士后学者和几名本科生将参与这个项目，学习他们在课堂上无法获得的技能。与当地一所高中正在进行的合作使本科生能够定期访问学校，谈论他们的工作，目的是在高中生中培养对科学的兴趣。