Introduction of Water-Vapor Broadening Parameters and Their Temperature-Dependent Exponents Into the HITRAN Database: Part I-CO2, N2O, CO, CH4, O2, NH3, and H2S.

Y Tan,R V Kochanov,I E Gordon,L S Rothman

doi:10.1029/2019jd030929

Abstract

The amount of water vapor in the terrestrial atmosphere is highly variable both spatially and temporally. In the tropics it sometimes constitutes 4–5% of the atmosphere. At the same time collisional broadening of spectral lines by water vapor is much larger than that by nitrogen and oxygen. Therefore, in order to accurately characterize and model spectra of the atmospheres with significant amounts of water vapor, the line‐shape parameters for spectral lines broadened by water vapor are required. In this work, the pressure‐broadening parameters (and their temperature‐dependent exponents) due to the pressure of water vapor for spectral lines of CO2, N2O, CO, CH4, O2, NH3, and H2S from both experimental and theoretical studies were collected and carefully reviewed. A set of semiempirical models based on these collected data was proposed and then used to estimate water broadening and its temperature dependence for all transitions of selected molecules in the HITRAN2016 database.

Highlights

Introduction of WaterVapor Broadening Parameters and Their Temperature‐Dependent Exponents Into the HITRAN Database: Part I—CO2, N2O, CO, CH4, O2, NH3, and H2SY
The HITRAN Application Programming Interface (HAPI; Kochanov et al, 2016) makes good use of these new parameters allowing the calculation of cross sections at different proportions of ambient gases (see Figure 31 of the HITRAN2016 paper (Gordon et al, 2017) for instance)
In this work the HITRAN database has been extended to include the water‐vapor broadening half‐widths as well as their temperature‐dependent exponents for CO2, O2, CH4, CO, NH3, N2O, and H2S based on semiempirical models

Summary

Introduction

The current edition of HITRAN2016 (Gordon et al, 2017) has substantially increased the potential for the database to model radiative processes in terrestrial and planetary atmospheres. The corresponding data for the CO molecule broadened by planetary gases was added from Li et al (2015) This has instigated a significant progress for generating high‐precision molecular absorption cross sections relevant to the studies of planetary atmospheres. This new initiative took full advantage of the new structure of the HITRAN database (see Hill et al, 2016) which allows storage and effective retrieval of these parameters. The HITRAN Application Programming Interface (HAPI; Kochanov et al, 2016) makes good use of these new parameters allowing the calculation of cross sections at different proportions of ambient gases (see Figure 31 of the HITRAN2016 paper (Gordon et al, 2017) for instance). The semiempirical models derived here can be applied to all isotopologues of the molecules in question

Generated Data Sets

Working With New Data Using HITRANonline and HAPI

Findings

Conclusions