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.

/pdf/the-hitran-2008-molecular-spectroscopic-database-1ud8clpej3.pdf

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 of all the J -multiplets between R (13) at 1375cm -1 and P (12) at 1225 cm -1 , in the v 4 -fundamental of 12 CH 4 , have been measured at 300°K. Our values are consistent with published band-intensity measurements and also with the theoretical line strength tabulation by Fox. Spectral transmittance computation using a Lorentz line shape with a hydrogen-broadened half-width of 0.075 cm -1 atm -1 at 300°K for all the lines in the band is in excellent agreement with our experimental data measured with a spectral resolution of 0.2 cm -1 . Our best estimate for the absolute intensity of the band is 145±8 cm -2 atm -1 at STP.

Intensity measurements in the v4-fundamental of methane☆

A theoretical formulation is presented within the framework of Anderson-Tsao- Curnutte theory for calculating the half-widths of spectral lines belonging to tetrahedral molecules. The importance of tetrahedral symmetry in the change distribution and in the wave functions is emphasized. Expressions for the interruption functions S 2 (b) have been derived for octopole-dipole, octopole-quadrupole, octopole-octopole, octopole-hexadecapole, hexadecapole- hexadecapole, anistropic dispersion interactions as well as for an assumed overlap interaction potential. The earlier theoretical work of Tejawni and Yamamoto and Hirono is shown to be inappropriate for molecules of tetrahedral symmetry.

Collision-broadened line widths of tetrahedral molecules—I. Theoretical formulation

Spectral absorption cross-sections k ν ( cm 2 molecule −1 ) were measured in the 7.07, 8.08, 9.24, 10.3, and 11.9 μm bands of HFC-134a at temperatures between 190 and 296 K and pressures between 10 and 1013 hPa with a high-resolution Fourier-transform spectrometer. Our data were obtained at pressures and temperatures that characterise several of the commonly adapted model atmospheres, represent tangent heights in solar-occultation-type remote-sensing observations of the atmosphere, and the conditions recorded in atmospheric observations at Arctic latitudes. The integrated cross-sections (or integrated intensities) of the absorption bands in the 7.07, 8.08, 9.24, 10.3, and 11.9 μm regions are, in the unit of 10 −17 cm molecule −1 , 0.4674, 9.711, 1.508, 0.8753, and 0.2527, respectively.

Absorption cross-sections of HFC-134a in the spectral region between 7 and 12 μm

Collision-broadened line widths in CO-CO2 and CO-O2 collisions have been calculated by incorporating interactions due to octopoles and hexadecapoles and short-range repulsive interactions into Anderson's (1949) theory. It is shown how these higher-order interactions can be manipulated to yield good agreement with experimental data. A critical evaluation of this totally empirical manipulation suggests that a thorough revision of the theory is required for all but simple dipole-dipole interactions. In the process of the evaluation, the values of the multipole moments are discussed.

/pdf/the-role-of-higher-multipolar-and-repulsive-forces-in-the-2f7ybl4l6t.pdf

The role of higher-multipolar and repulsive forces in the calculation of collision-broadened line-widths of linear molecules

Rotational half-widths have been computed at 220°K, 250°K, 280°K, and 300°K for air-broadened absorption lines of N2O using the Anderson-Tsao-Curnutte theory. The new results are compared with previously available estimates at 300°K. Self-broadened line widths have also been computed at 300°K; good agreement has been obtained with Goody's data.

Prasad Varanasi

Papers

Intensity measurements in the v4-fundamental of methane☆

Collision-broadened line widths of tetrahedral molecules—I. Theoretical formulation

Absorption cross-sections of HFC-134a in the spectral region between 7 and 12 μm

The role of higher-multipolar and repulsive forces in the calculation of collision-broadened line-widths of linear molecules

Theoretical line widths in N2O-N2O and N2O-air collisions