Molecular spectroscopy - molecular spectroscopy is a key method to determine the spectral signature of the Earth and the
other planets of the Solar system, as well as the exoplanets. It aims at recording the electromagnetic
radiation reflected or emitted by a target (surface or atmosphere) in very narrow wavebands. In particular it
plays an essential role in the monitoring of the evolution of our atmosphere (aerosols and gas molecules).
In the next decades, large telescopes will extend observation to new spectral domains and boost the
search for life on exoplanets. New instruments designed to analyze the chemical composition of the Earth's
lower atmosphere (greenhouse gases, pollutants, etc.) use technologies that allow measurements of
spectra with very high spectral resolution and signal-to-noise ratios. The interpretation of these spectra
requires mastering theoretical and experimental spectroscopic analysis techniques.
- Introduction to radiative transfert this lecture introduces the concepts of direct and inverse radiative transfer, which underlie the
study of the Earth's atmosphere using remote sensing satellites, in the context of climate studies. The
physical variables and fundamental laws are reminded, leading to the derivation of the radiative transfer
equation that calculates the electromagnetic radiation transmitted or emitted by the atmosphere and
measured at the top of it. This equation involves various thermodynamic, spectroscopic and instrumental
information. The main radiative transfer codes are described. Finally, the inverse problem that consist in
extracting atmospheric variables from radiometric measurements is discussed and illustrated by numerous
examples involving present space missions.
