Accuracy Improvement and Uncertainty Reduction of Spectroscopic Parameters of Water Vapor Lines in the HITRAN Database

本项目的主要目的是为更新和完善HITRAN数据库中的水汽分子参数提供理论支持。HITRAN中水蒸气的主要氧同位素的压力加宽半宽度、诱导线位移和温度指数的最新变化主要来自依赖于Robert-Bonamy形式主义的理论计算，该形式主义是三十多年前开发的，包含几个近似值。从第一性原理直接计算这些光谱参数的特点是理论上的复杂性以及数值上的困难。所提出的方法提供了几个新的功能和优势。首先，重新制定的罗伯特-波纳米形式主义表明，删除一个削弱近似实际上减少了计算负担。其次，在希尔伯特空间中引入坐标表示使得能够使用足够高的截止值来保证所有计算的完全收敛。第三，不同碰撞过程的贡献分析为势能模型优化中基准线的选择提供了新的指导。此外，采用信号处理中的因果函数概念来获得希尔伯特变换，这在计算线位移中至关重要，允许计算向前进行，甚至不必执行柯西主积分。有了这些强有力的工具在手，加宽的半宽度，线位移，和温度指数的纯转动带中的吸收线将重新计算？所有这些都是完全收敛的，并且来自“精确”轨迹模型。这些结果将大大减少数值不确定性，从而比HITRAN 2008中现有的计算值更可靠。可靠的空间和地面仪器信息反演以及可靠的气候和大气模拟直接依赖于HITRAN提供的准确的水汽光谱参数。许多不同学科的研究科学家都期望HITRAN的高质量作为他们不可或缺的数据资源，必须是正确的。HITRAN水汽光谱参数的更新将提高辐射传输建模的准确性，例如控制寒冷和干燥极地大气中局部能量平衡的20微米“脏窗”光谱区域。本文所述的计算方法不仅适用于纯转动带中的水汽谱线，而且也适用于其它带。此外，它也可以用来预测线参数，涉及非常高的j状态的HIEMP，一个项目的发展，旨在解决高温建模的分子气体光谱所需的天体物理学，行星和恒星大气，以及工业，环境和监视应用。

The primary objective of this project is to provide theoretical support for updating and improving parameters for the water vapor molecule in the HITRAN database. The latest changes made to the pressure broadened half-width, induced line shift, and temperature exponent for the principal oxygen isotopologue of water vapor in HITRAN come mostly from theoretical calculations that rely on the Robert-Bonamy formalism, which was developed more than three decades ago and contains several approximations. Direct calculation of these spectroscopic parameters from first principles is characterized by theoretical complexity as well as numerical difficulty. The proposed approach offers several new features and advantages. First, re-formulating the Robert-Bonamy formalism shows that the removal of one debilitating approximation actually reduces the computational burden. Second, introducing the coordinate representation in Hilbert space enables the use of sufficiently high cut-offs to guarantee full convergence for all the calculations. Third, contribution analysis from different collisional processes establishes a new guideline for selecting benchmark lines in optimizing the potential model. Furthermore, the adoption of the causal function concept from signal processing to obtain the Hilbert transforms, crucial in calculating line shifts, allows the calculations to go forward without even having to perform the Cauchy principal integrations. With these powerful tools in hand, the broadened half-widths, line shifts, and temperature exponents for the absorption lines in the pure rotational band will be recalculated ? all with full convergence and from the "exact" trajectory model. These results will significantly reduce the numerical uncertainties, and are thus more reliable than the existing calculated values in HITRAN 2008.Reliable information retrieval using space and ground-based instruments, and reliable climate and atmospheric modeling are directly dependent on accurate water vapor spectroscopic parameters provided by HITRAN. Research scientists in many different disciplines have come to expect the high quality of HITRAN as their indispensable data resource that simply must be correct. The updating of the HITRAN water vapor spectroscopic parameters will improve the accuracy of radiative transfer modeling, such as the 20 micrometer 'dirty window' spectral region that controls the local energy balance in the cold and dry polar atmospheres. The computational approach described herein is applicable not only to the water vapor lines in the pure rotation band, but to other bands as well. Moreover, it can also be used to predict line parameters that involve very high j states in the development of HITEMP, a project designed to address high-temperature modeling of the spectra of molecular gases needed for astrophysics, planetary and stellar atmospheres, as well as industrial, environmental, and surveillance applications.