Sandrine GUERLET

Researcher -- Planetary atmospheres

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• ANR SOUND
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Welcome ! I am a CNRS researcher at Laboratoire de Météorologie Dynamique (LMD), currently head of the "Planeto" team. My research work focuses on the modeling and remote sensing of planetary atmospheres. I am particularly interested in the study of atmospheric composition, thermal structure, radiative balance, dynamics and climate of giant planet atmospheres. To achieve these goals, I acquired expertise in the analysis of infrared spectroscopic observations through the development of radiative transfer models and retrieval algorithms, and in climate modeling through contributions to the development of a generic General Circulation Model, called the LMD Planetary Climate Model, used in our team to model any kind of planetary atmosphere.

Research activities

My main research activities focus on the study of Jupiter and Saturn atmospheres, both from remote sensing observations (Cassini/CIRS, ground-based observations) and via the development of the "giant planet" version of the LMD Planetary Climate Model, in collaboration with other colleagues. I have had the chance to be strongly involved in the Cassini-Huygens mission as a Co-I of the CIRS instrument (a thermal infrared spectrometer), and I am currently a scientific team member of MAJIS, an imaging spectrometer onboard the ESA JUICE mission. I am particularly interested in the study of (seasonal) variations in stratospheric temperatures, composition, and dynamics (wave activity, equatorial oscillation), in the study of the impact of ion precipitation at high latitudes on the stratospheric thermal structure and composition, and more recently in tropospheric dynamics and storm activity.

In the period 2021-2025, I led a projet focused on studying the dynamics of Uranus and Neptune's atmospheres both through analysis of observations (from ALMA) and through the development of two types of model: a General Circulation Model to study large-scale dynamics, and a Cloud Resolving Model to study small-scale storm dynamics. This project, named SOUND, was funded by the French ANR and achieved in collaboration with researchers at LIRA/Observatoire de Paris and the Laboratoire d'Astrophysique of Bordeaux. Although funding is officially over, we are continuing these collaborative research activities.

I have also been strongly involved in the ExoMars Trace Gas Orbiter mission, as a co-I of the ACS suite of spectrometers. I was in charge, on the French side, of the development of the retrieval pipeline for the thermal infrared data analysis. This led me to characterize diurnal variations in temperature and dust in the Martian troposphere, with a focus on the study of thermal tides properties, both before and during the 2018 Global Dust Storm. These results were also exploited in a data assimilation scheme, coupled to our group's Mars Planetary Climate Model.

Finally, I also have experience on Earth remote sensing, especially acquired during a postdoc focused on the analysis of swhortwave infrared spectra acquired by the Japanese GOSAT satellite, with the goal of mapping CO2 and CH4 concentrations. More recently, I have also analysed spectra acquired by MAJIS onboard JUICE during a gravity assist manoeuver (a Moon-Earth flyby in 2024), and compared these observations to co-located ones by the IASI instrument, to assess the (excellent!) performances of MAJIS.

Besides research, I am also involved in various outreach activities by volunteering to public events, acting as a guide at the Paris Observatory, giving public talks, or helping with school projects. With three other great colleagues I am also proud to have written a book on the Saturn System (in French), called "Les mondes de Saturne".