Adequate tools are required to perform reliable radiative transfer modelling calculations to
meet the needs of communities involved in understanding the atmospheres of the Earth and
other planets. Among these tools compilations of spectroscopic parameters are used for a vast
array of applications and especially for planetary atmospheric remote sensing. Consequently,
there is an acute need for comprehensive, trustworthy and operational interactive spectroscopic
databases to benefit the research in direct and inverse radiative transfer. In this context, since
over three decades, the ARA (Atmospheric Radiation Analysis) group at LMD (Laboratoire de
Météorologie Dynamique, France) has developed GEISA (Gestion et Etude des Informations
Spectroscopiques Atmosphériques: Management and Study of Atmospheric Spectroscopic
Information), a computer accessible database system [Chédin et al. (1982), Husson et al.
(1992), Jacquinet-Husson et al. (1999, 2005, 2008, 2011, 2016), Armante et al (2016), designed to facilitate accurate and fast forward,
calculations of atmospheric radiative transfer using a line-by-line and (atmospheric)
layer-by-layer approach. This effort has proven to be beneficial to the atmospheric scientific
community participating in direct and inverse radiative transfer studies.
The role of molecular spectroscopy in modern atmospheric research has entered a new phase
with the advent of highly sophisticated spectroscopic instruments and computers. For example,
the performance of Earth atmospheric sounders like AIRS, in the
USA, and IASI in Europe, which have a better vertical
resolution and accuracy, compared to the previous existing satellite infrared vertical sounders,
is directly related to the quality of the spectroscopic parameters of the optically active gases,
since these are essential input in the forward models used to simulate recorded radiance spectra.
Consequently, a strong demand exists for highly comprehensive, well validated, efficiently
operational, and desirably interactive computer-based spectroscopic databases to benefit the
research in direct and inverse radiative transfer.
In this purpose, GEISA is currently involved in activities related to the assessment of the
Since the METOP European polar satellite launch (October 19th 2006, october 2012)
, GEISA is the reference spectroscopic database for the
validation of the level-1 IASI data (CAL/VAL activities), using the 4A (Automatized Atmospheric Absorption Atlas)
radiative transfer model [Scott (1974), Scott and Chédin (1981); 4A/LMD
; 4A/OP co-developed by LMD and Noveltis
with the support of CNES].
GEISA is maintained :
by the Ara group at LMD (Ecole Polytechnique) for its scientific part.
by the AERIS/ ESPRI Data Centre (former Ether) group (CNRS Centre National de la Recherche Scientifique-France) at IPSL (Institut Pierre Simon Laplace) for its technical part.
|Last update : December 2017