The 2009 edition of the GEISA spectroscopic database

Abstract

The updated 2009 edition of the spectroscopic database GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphé riques; Management and Study of Atmospheric Spectroscopic Information) is described in this paper. GEISA is a computer-accessible system comprising three independent sub-databases devoted, respectively, to: line parameters, infrared and ultraviolet/visible absorption cross-sections, microphysical and optical properties of atmospheric aerosols. In this edition, 50 molecules are involved in the line parameters sub-database, including 111 isotopologues, for a total of 3,807,997 entries, in the spectral range from 10 À 6 to 35,877.031 cm À 1. The successful performances of the new generation of hyperspectral sounders depend ultimately on the accuracy to which the spectroscopic parameters of the optically active atmospheric gases are known, since they constitute an essential input to the forward radiative transfer models that are used to interpret their observations. Currently, GEISA is involved in activities related to the assessment of the capabilities of IASI (Infrared Atmospheric Sounding Interferometer; http://smsc.cnes.fr/IASI/index.htm) on board the METOP European satellite through the GEISA/IASI database derived from GEISA. Since the Metop-A (http://www.eumetsat.int) launch (19 October 2006), GEISA is the reference spectroscopic database for the validation of the level-1 IASI data. Also, GEISA is involved in planetary research, i.e., modeling of Titan's atmosphere, in the comparison with observations performed by Voyager, or by ground-based telescopes, and by the instruments on board the Cassini-Huygens mission. GEISA, continuously developed and maintained at LMD (Laboratoire de Mé té orologie Dynamique, France) since 1976, is implemented on the IPSL/CNRS (France) ''Ether'' Products and Services Centre WEB site (http://ether.ipsl.jussieu.fr), where all archived spectroscopic data can be handled through general and user friendly associated management software facilities. More than 350 researchers are registered for on line use of GEISA.

First theoretical global line lists of ethylene (12C2H4) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

“…The corresponding statistics are discussed in the last section of the paper. Ethylene spectral data in the far-infrared are included in several empirical databases such as HITRAN, GEISA, and EcaSDa (Rothman et al 2013;Jacquinet-Husson et al 2011;Ba et al 2013), and some lines are accessible at the internet portal of the VAMDC center (Rixon et al 2011;Dubernet-Tuckey et al 2016). Most of them are based on line-by-line analyses of experimental laboratory room-T spectra.…”

“…A significant number of hot-band transitions contribute to the ethylene opacity even at room temperature because the torsion modes lie below 1000 cm −1 . Because of difficulties in analyses of congested laboratory infrared spectra, the ethylene line-by-line information in available spectroscopic databases (Rothman et al 2013;Jacquinet-Husson et al 2011), essentially composed of coldband transitions from the ground state, is far from being complete for accurate opacity calculations. No high-temperature laboratory intensity data are available.…”

Spectroscopy of planetary atmospheres in our Galaxy

“…Top: T = 300 K; bottom: T = 1200 K. The spectral resolution is 10 cm −1 , which corresponds to a resolving power of 67 at 16 μm, 100 at 10 μm and 500 at 2 μm. The spectroscopic parameters are taken from the GEISA data base (Jacquinet-Husson et al 2011) and ground-based facilities, modelling exoplanetary spectra in this spectral range is complicated by the complexity of the molecular signatures. Many weak bands (typically overtone and combination bands) are present between 1 and 2 μm.…”

“…Top: T = 300 K; bottom: T = 1200 K. The spectral resolution is 25 cm −1 , which corresponds to a resolving power of 200 at 2 μm, 300 at 1.67 μm and 400 at 1 μm. The spectroscopic parameters are taken from the GEISA data base (Jacquinet-Husson et al 2011). The data base is known to be incomplete, especially in the case of CH 4 (see text) Fig.…”

“…High-temperature spectroscopic data cannot be extrapolated from low temperature atmospheric database such as the most currently used HITRAN (Rothman et al 2013) and GEISA (Jacquinet-Husson et al 2011). Such extrapolations fail to reproduce high J rovibrational transitions and hot band transitions involving highly excited vibrational levels.…”