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

这个项目涉及发展一个理论模型，以计算地球和行星大气中气体的压力加宽半宽度和压力引起的线移及其对温度的依赖关系，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行模式的主要误差来源。由于需要许多不同气体的成千上万的无振动跃迁数据，因此需要一种基于物理的计算效率高的理论模型，可以正确地确定线形参数。半经典复罗伯特-博纳米形式主义是理论方法的基础。为了对所有跃迁都有好的结果，不仅仅是强谱，分子间势必须扩展到非常高的阶，分子动力学必须使用汉密尔顿方程。对于近红外和可见光谱区域的跃迁，需要更好的波函数和能量，因为经典的有效哈密顿测定失效了。利用从头算能量和波函数来确定约简矩阵元是一种补救问题的方法。研究了碰撞诱发参数的振动状态、旋转状态和温度依赖关系。由于星载光谱仪的改进，线形模型需要改进。虽然Voigt模型构成了线形的基础，但Dicke变窄和速度依赖的修正及其相关性必须在这项工作中得到考虑。由此产生的数据将大大改善线形参数及其温度依赖性，通过减少模型中使用的半宽度和其他线形参数的不确定性，帮助研究人员进行浓度和温度剖面检索以及地球和其他行星热平衡的辐射传输研究。这项工作将提高光谱遥感结果的可信度，并使我们能够更好地确定温室气体的辐射强迫。提高对地球能量平衡的认识将有助于做出更明智的政策决定。数据将通过HITRAN、HITEMP、GEISA和IUPAC（水蒸气）数据库和主要研究者的网站进行分发。一名博士后学者和几名本科生将参与这个项目，学习他们在课堂上学不到的技能。与当地一所高中正在进行的合作，允许本科生定期访问学校，谈论他们的工作，目的是在高中生中创造对科学的兴趣。

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.