Bruno Bézard

The 2018 David Bates Medal is awarded to Bruno Bézard for his pioneering analysis of spectroscopic observations to characterise planetary atmospheres.

Bruno Bézard work is internationally recognised and he is known as one of the brightest analysts of remote and in situ spectroscopic observations – from the visible to the millimetre range – to characterise planetary atmospheres. His expertise covers all facets of the field, including molecular spectroscopy, forward radiative transfer modelling, retrieval techniques, and physical interpretation in terms of thermal, chemical and dynamical properties of planetary atmospheres. He has made outstanding contributions to our knowledge of the composition and the structure of the atmospheres of all planets of our solar system as well as of exoplanets. He pioneered the detection of several molecules and isotopes in Venus, Jupiter, Saturn, Titan and Neptune.

Bézard’s intimate knowledge of spectroscopy makes him an essential link between observers and laboratory spectroscopists. He has a global view of the spectroscopic needs of the planetary community and initiated many laboratory measurements, with the aim of detecting new molecules or improving the retrieval of atmospheric parameters. He has extensively published in peer-reviewed journals and his work has been widely cited. Bézard’s early work was related to the time-varying composition and thermal structure of giant planet atmospheres from visible to infrared, using ground-based and Voyager observations. He developed seasonal radiative models for Jupiter, Saturn and Uranus, at the time the most elaborate worldwide. He then extended his work to the study of the atmospheres of Venus, Titan, Mars and of exoplanets. His contribution to our understanding of Venus atmosphere is widely recognised. He served as a co-investigator for the Venus Express mission and as the coordinator of the ‘Radiative transfer working group’ of the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS). He is the chief editor of the Venus III book, which is likely to be the reference book regarding Venus for many years to come.

Since the Voyager era, Bézard made extensive contributions to the study of Titan’s atmosphere. He served as a co-investigator in the Cassini-Huygens mission for the Cassini Composite Infrared Spectrometer (CIRS) and as the task leader of the atmospheric modelling group. He also served co-investigator of the Huygens Descent Imager/Spectral Radiometer (DISR) instrument supervising the French contribution, i.e. the supply of the infrared sub-systems. He contributed in major ways to the study of the thermal budget of Titan combining both DISR and CIRS measurements, as well as in many of the CIRS papers on the composition of Titan’s atmosphere.
Bézard did not miss the ‘exoplanet revolution’. As early as 2000, he built with two successive PhD students one of the first time radiative-equilibrium models of hot Jupiters. While supervising another PhD, he recently developed a new version of his model, adapted to the interpretation of spectra of young exoplanets that can be directly imaged and characterised in the infrared from the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument on the Very Large Telescope instrument, and soon from space with the James Webb Space Telescope.

Bézard is known as an excellent lecturer. His course, a comprehensive discussion of all of the aspects of planetary atmospheric physics and chemistry has stayed as a reference for many in the field. Bruno Bézard undoubtedly deserves to be recognised with the EGU 2018 David Bates Medal.