GEISA-97 overview

 

OVERVIEW OF THE 1997 EDITION OF THE GEISA SPECTROSCOPIC DATABANK

    The 1997 version of the GEISA databank (hereafter referred to as GEISA-97) contains line parameters for 42 molecules (96 isotopic species) with 1,346,266 entries between 0 and 22,656 cm-1. It has molecules of interest for both terrestrial and other planetary atmospheres (for example, C2H4, GeH4, C3H8, C2N2, C4H2, HC3N, H2S, HCOOH and C3H4, for the Giant Planets). GEISA-97 has been developed in close cooperation with the contributors of three spectroscopic databases, ATMOS-95 (Atmospheric Trace Molecule Spectroscopy) (Brown et al., 1996), HITRAN-96 (HIgh resolution TRANsmission) (Rothman et al., 1998) and TDS (Tomsk Dijon Spectroscopic project; Traitement des Données Spectroscopiques)/STDS (Spherical Top Data System) (Tyuterev et al., 1994; Wenger and Champion, 1998).

        Since the release of the former edition in 1992 (Husson et al., 1992; 1994), hereafter referred to as GEISA-92 , two new species, HO2 and ClONO2, (formerly only present in the cross-sections file of GEISA-92), have been added for the first time, and seventeen existing molecules: O3, N2O, CH4, NO, SO2, NO2, NH3, HNO3, OH, ClO, OCS, 13C12CH6, CH3D, C2H2, C2H4, H2O2, H2S, have been updated for GEISA-97. These changes have added 10 new isotopes: three for the new molecules and seven for the already existing molecules (two in O3, one in CO, two in OCS, one in C2H6, and one in C2H4) and the parameters of nineteen species have been updated or included.

        In the detailed summary of the line parameters in GEISA-97  , in Table 1, the items listed for each molecular species, given in column 1, are: the identification code (ID codes defined for the GEISA management software in Chedin et al., 1985, 1986), the number of lines, the intensity average, the mean halfwidth at half maximum, the identification codes of its various isotopes, and for each isotope: the number of lines, the transitions minimum and maximum wavenumbers (in cm-1), and the lines intensities minimum and maximum values (in cm molecule-1), in columns 2 to 11, respectively.

       In addition to the individual lines spectroscopic data catalog, GEISA-97 also has a catalog of cross-sections at different temperatures and pressures for species (such as chlofluorocarbons) with complex spectra that are too dense for discrete parameterization.

The current version of the GEISA-97 cross-sections database contains 4,716,743 entries related to 23 molecules. In the GEISA-97 cross-sections file content informations, summarized in Table 2, in the first column are listed the molecules included with their name (for the CFC's) and corresponding chemical formula; colums 2 and 3 provide the cross-sections spectral intervals availability and temperature conditions; the related author references are in column 4. It should be noted that, for the majority of the molecules, the database comprises cross-sections for a set of temperatures and pressures corresponding to layers of the US standard atmosphere models, that allows simulations of the radiation propagation along slant paths in the atmosphere. Usually, the cross-sections are provided at uniform frequency steps for a given molecule, as in the case of the data listed in Table 2, except for the ones of Li and Varanasi, 1994; Varanasi and Nemtchinov, 1994; Varanasi et al., 1994, which are not given on uniform cm-1 net steps. They were recorded for different conditions of pressure and temperature, at different resolutions, whith corresponding different step sizes.   

  

REFERENCES

 

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