This paper describes the contents of the 2016 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2012 and its updates during the intervening years. The HITRAN molecular absorption compilation is composed of five major components: the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, collision-induced absorption data, aerosol indices of refraction, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, added line-shape formalisms, and validity. Moreover, molecules, isotopologues, and perturbing gases have been added that address the issues of atmospheres beyond the Earth. Of considerable note, experimental IR cross-sections for almost 300 additional molecules important in different areas of atmospheric science have been added to the database. The compilation can be accessed through www.hitran.org. Most of the HITRAN data have now been cast into an underlying relational database structure that offers many advantages over the long-standing sequential text-based structure. The new structure empowers the user in many ways. It enables the incorporation of an extended set of fundamental parameters per transition, sophisticated line-shape formalisms, easy user-defined output formats, and very convenient searching, filtering, and plotting of data. A powerful application programming interface making use of structured query language (SQL) features for higher-level applications of HITRAN is also provided.

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The HITRAN 2008 molecular spectroscopic database

The JRA-55 Reanalysis: General Specifications and Basic Characteristics

Description of the NCAR Community Atmosphere Model (CAM 3.0)

We examine the sensitivity of a climate model to a wide range of radiative forcings, including changes of solar irradiance, atmospheric CO2, O3, CFCs, clouds, aerosols, surface albedo, and a “ghost” forcing introduced at arbitrary heights, latitudes, longitudes, seasons, and times of day. We show that, in general, the climate response, specifically the global mean temperature change, is sensitive to the altitude, latitude, and nature of the forcing; that is, the response to a given forcing can vary by 50% or more depending upon characteristics of the forcing other than its magnitude measured in watts per square meter. The consistency of the response among different forcings is higher, within 20% or better, for most of the globally distributed forcings suspected of influencing global mean temperature in the past century, but exceptions occur for certain changes of ozone or absorbing aerosols, for which the climate response is less well behaved. In all cases the physical basis for the variations of the response can be understood. The principal mechanisms involve alterations of lapse rate and decrease (increase) of large-scale cloud cover in layers that are preferentially heated (cooled). Although the magnitude of these effects must be model-dependent, the existence and sense of the mechanisms appear to be reasonable. Overall, we reaffirm the value of the radiative forcing concept for predicting climate response and for comparative studies of different forcings; indeed, the present results can help improve the accuracy of such analyses and define error estimates. Our results also emphasize the need for measurements having the specificity and precision needed to define poorly known forcings such as absorbing aerosols and ozone change. Available data on aerosol single scatter albedo imply that anthropogenic aerosols cause less cooling than has commonly been assumed. However, negative forcing due to the net ozone change since 1979 appears to have counterbalanced 30–50% of the positive forcing due to the increase of well-mixed greenhouse gases in the same period. As the net ozone change includes halogen-driven ozone depletion with negative radiative forcing and a tropospheric ozone increase with positive radiative forcing, it is possible that the halogen-driven ozone depletion has counterbalanced more than half of the radiative forcing due to well-mixed greenhouse gases since 1979.

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/96JD03436

Radiative forcing and climate response

Since its first publication in 1973, the HITRAN molecular spectroscopic database has been recognized as the international standard for providing the necessary fundamental spectroscopic parameters for diverse atmospheric and laboratory transmission and radiance calculations. There have been periodic editions of HITRAN over the past decades as the database has been expanded and improved with respect to the molecular species and spectral range covered, the number of parameters included, and the accuracy of this information. The 1996 edition not only includes the customary line-by-line transition parameters familiar to HITRAN users, but also cross-section data, aerosol indices of refraction, software to filter and manipulate the data, and documentation. This paper describes the data and features that have been added or replaced since the previous edition of HITRAN. We also cite instances of critical data that are forthcoming.

https://hitran.org/media/refs/HITRAN-1996.pdf

The hitran molecular spectroscopic database and hawks (hitran atmospheric workstation): 1996 edition

The absolute intensities and collision-broadened half-widths of several lines in the P-,Q-, and R-branches of the nu5-fundamental band of (C-12)2H2 have been measured at various temperatures between 147 and 295 K employing the Doppler-limited spectral resolution (about 10 exp -4/cm) of a tunable diode laser spectrometer. The absolute intensities of R(5), R(7), R(9), and R(20) in the same fundamental belonging to (C-12)(C-13)H2 have also been measured at 294 K. The temperature dependence of the collision-broadened half-width has been determined for some of the lines broadened by planetary atmospheric gases, namely, He, Ar, H2, and N2. Four self-broadened linewidths of (C-12)2H2, as well as three H2-broadened linewidths and a self-broadened half-width of (C-12)(C-13)H2, have also been retrieved from the measurements.

Intensity and linewidth measurements in the 13.7 μm fundamental bands of 12C2H2 and 12C13CH2 at planetary atmospheric temperatures

Employing the techniques that we have described previously for measuring infrared (i.r.) lineshifts, linewidths and line intensities with a tunable diode laser, we have measured these parameters for lines in the R(4) and R(7) multiplets of the v4-fundamental band of 12CH4 at 161, 209 (or 218) and 295 K using He, Ne, Ar, H2, N2, O2, and air as the perturbers. The temperature dependence of the collision-induced lineshift is markedly different from that of the corresponding collision-broadened linewidth.

The temperature dependence of lineshifts, linewidths and line intensities of methane at low temperatures

High-resolution measurements of the absolute intensities, self- and air-broadened half-widths, self- and air-induced line shifts, and the variation of these parameters with temperature are presented for the infrared lines of water vapor in the 610–2100 and the 3000– 4050 cm −1 spectral regions. In this study spectral lines belonging to the ν 1 , ν 2 , ν 3 , and 2 ν 2 bands as well as the weak lines of the pure-rotational spectrum have been studied and the dependence of some of the line parameters on the vibrational quantum number has been studied.

Laboratory measurement of the spectroscopic line parameters of water vapor in the 610–2100 and 3000–4050 cm−1 regions at lower-tropospheric temperatures

Diode laser line strength measurements of the (ν4 + ν5)0 band of 12C2H2

Anderson–Tsao–Curnutte theory of collision‐broadened spectral lines has been extended to octopolar molecules, and the results are applied to the rotational lines in the ν3 band of methane. Calculated half‐widths are in excellent agreement with the high‐resolution measurements of Varanasi for self‐broadening and broadening by N2, O2, H2, and He. The theory has also been applied to CO lines broadened by CH4 and to CH4 lines broadened by HCl. The excellent agreement with experimental data in both the cases leads to the estimate of Ω = 5.0 × 10−34esu·cm3 for the octopole moment of CH4.

Prasad Varanasi

Papers

Intensity and linewidth measurements in the 13.7 μm fundamental bands of 12C2H2 and 12C13CH2 at planetary atmospheric temperatures

The temperature dependence of lineshifts, linewidths and line intensities of methane at low temperatures

Laboratory measurement of the spectroscopic line parameters of water vapor in the 610–2100 and 3000–4050 cm−1 regions at lower-tropospheric temperatures

Diode laser line strength measurements of the (ν4 + ν5)0 band of 12C2H2

Calculation of Collision‐Broadened Linewidths in the Infrared Bands of Methane