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The ARA group at LMD has a long experience in the 3-D
analysis of the thermodynamic state of the atmosphere from
satellite remote sounding and in the forward and inverse radiative
transfer problems for the Earth and planetary atmospheres, from
near infrared to microwaves. One of its main goals is the study of
the climate variability and evolution from the coupling of
satellite observations (vertical sounding, imagery) and modeling of
the atmospheric circulation and climate. The group has developed
and applied a variety of forward and inverse methods for deriving
and analyzing long time series of climate variables (temperature,
humidity, cloud field mesoscale and microphysical properties,
surface characteristics as temperature and emissivity,
concentration of main greenhouse gases, etc.) at global scale (NOAA
/NASA Pathfinder programme). The group is in charge of designing
new methods (for example, based on neural networks) for the
processing and interpretation of the new observing systems as
AIRS/EOS/NASA or IASI/CNES/EUMETSAT. The ARA group has participated
in the European Union FP5 project “COCO”, in charge of
the observation of CO2 from space.
Alain Chédin is Directeur de Recherche at
CNRS and Senior Scientist at LMD. After his work in theoretical
molecular spectroscopy at Université Pierre et Marie Curie
(Paris-6), he joined the LMD in 1976 to create the Atmospheric
Radiation Analysis (ARA) group. He is involved in atmospheric
spectroscopy and radiative transfer (direct and inverse) and
application of these methods to climate studies from a coupling
between satellite observations, modeling and sophisticated
statistical methods for analysis of trends and variations. He is
(or was) PI or Co-I of International Projects (as GEWEX-GVap,
NOAA/NASA Pathfinder Program, ATSR, AIRS, IASI). Former Secretary
of the International Radiation Commission (IRC). He is the former
chairman of scientific working groups of the IRC as ITRA (Inter
comparison of Transmittance and Radiance Algorithms), ITSC
(International TOVS Study Conference). He was also Chairman of the
CNES Earth-Ocean-Atmosphere-Biosphere working group and member of
its Scientific Program Committee. He has acted as scientific
advisor of the CEA (Commissariat à l'Energie Atomique)
General Administrator and was a member of the French Minister of
Higher Education and Research’s staff. He is a member of the
Global Carbon Project (GCP). He recently pioneered a research on
retrieving global scale atmospheric CO2 concentration
from infrared space observation.
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