HITRAN

The knowledge of spectroscopic parameters for transitions between energy levels in molecules (and atoms) is essential for interpreting and modeling the interaction of radiation (light) within different media.

[2] The original version of HITRAN was compiled by the US Air Force Cambridge Research Laboratories (1960s) in order to enable surveillance of military aircraft detected through the terrestrial atmosphere.

[2] One of the NASA missions currently utilizing HITRAN is the Orbiting Carbon Observatory (OCO) which measures the sources and sinks of CO2 in the global atmosphere.

Typically HITRAN includes absorption cross-sections for heavy polyatomic molecules (with low-lying vibrational modes) which are difficult for detailed analysis due to the high density of the spectral bands/lines, broadening effects, isomerization, and overall modeling complexity.

[10][1] There are numerous applications for HITEMP data, some examples include the thermometry of high-temperature environments,[13] analysis of combustion processes,[14] and modeling spectra of atmospheres in the Solar System,[15] exoplanets,[16] brown dwarfs,[17] and stars.

[18] A Python library HAPI (HITRAN Application Programming Interface) has been developed which serves as a tool for absorption and transmission calculations as well as comparisons of spectroscopic data sets.

In addition to accounting for pressure, temperature and optical path length, the user can include a number of instrumental functions to simulate experimental spectra.

[19] The following spectral functions can be calculated in the current version #1 of HAPI:[20] HAPIEST (an acronym for HITRAN Application Programming Interface and Efficient Spectroscopic Tools) is a graphical user interface allowing users to access some of the functionality provided by HAPI without any knowledge of Python programming, including downloading data from HITRAN, and plotting of spectra and cross-sections.