High Resolution Spectra

en cours ...

The data-exchange project described hereafter was initiated in the frame of
  • ANR $N^o$ 07 BLAN 127 03 ``Exoclimat''
  • RTRA ITAAC $N^o$ STAE/2008/PS/002 ``Impact du Trafic Aérien sur l'Atmosphère et le Climat''
  • GDR
  • ERC ??
  • autres ??
It is widely inspired from the LXcat plasma data-exchange project. It can also be partly compared to the gas mixture spectra on the web section of the HITRAN project, as well as the cross section page of the ExoMol project.

Our objective is to archive high-resolution absorption spectra of molecular gases and provide softwares for computation of effective parameters such as emissivities, k-distributions, or parameters of narrow band average transmissivities and wide band models.

Three steps are followed by radiative transfer physicists when they need high-resolution absorption-spectra of gas-mixtures at given temperatures and pressures (assuming a state of equilibrium), throughout given frequency intervals (commonly as wide as the whole infrared plus visible plus ultraviolet, including hundreds of milions of absorption line centers) :

Molecular transition databanks (Step 1) are already quite exaustive and accurate and are being continuously refined by an active and well structured community. The HITRAN project is undenialbly the most illustrative of these structuration efforts.

But as soon as the considered thermodynamic conditions or the considered distances are outside the range typical of either the terrestrial atmosphere or the most common combustion devices, the question of modeling line shapes and collision induced continuum is widely open. Each group of radiative transfer physicists makes then its own physical choices (Step 2) and adjusts its numerical tools accordingly (Step 3). Consequently, until dedicated efforts are made collectively by the community of advanced-spectroscopy users (expecting it not from advanced-spectroscopy experts that have other concerns) :

The above statements are particularly illustrative of the astrophysics-radiation recent history, but the rapidely increasing accuracy requirements of the combustion research community defines strictly identical questions (as far as both heat transfer and optical diagnosis are concerened).

At the present stage we opened a brainstorming session within the STARWest community and we only uploaded what we called the level-zero databank :

This caricatural databank is meant to serve as a ground-reference for forthcomming uploads, but it can already be used with confidence for numerous engineering applications. It was used in particular within the ITAAC contrail simulation project.

Each spectrum corresponds to a single gas mixed with pure air, with molar fractions ranging from $x=0.01$ to $x=1$, temperatures ranging from $T=300K$ to $T=1500K$ and pressures ranging from $P=0.4 bar$ to $P=40 bar$.

Richard Fournier 2012-06-13