Troposphere-stratosphere interactions

Our work on troposphere-stratosphere interactions follows observational, theoretical and modelling approaches. Our observational component consists in developing innovative instruments, coordinating and participating in field campaigns. Observational data are used to validate theories and improve representation of dynamical processes in atmospheric models

Strateole 2

Strateole-2 is a French-US project to study climate processes in the vicinity of the tropopause tropical layer. The project originality pertains to  the use of CNES superpressure balloons, capable of drifting for several months between 18 and 20 km altitude. Two field campaigns occurred during 2019-2020 and 2021-2022 periods. The above figure shows the balloons launched during the 2019-2020 period (left) and balloon measurements of gravity wave activity as function of the distance to convection (right). It shows the larger variability of gravity wave activity closer to the convection and suggest preferred generation of gravity waves at specific stage of the convection.

Gravity-wave parameterizations in climate models

Observational datasets are useful to develop and validate parameterizations of gravity waves in climate models. The team is involved in different international programmes: QBOi (Quasi Biennal Oscillation initiative) which aims at better understanding QBO evolution under climate change and DataWave promoting the  development of new gravity wave parameterization using machine learning techniques.

Stratospheric plumes generated by volcanoes eruptions and huge wild fires

Several major aerosols emission events in the stratosphere produced by large forest fires and volcanoe eruptions occurred during the recent years: Canadian wild fires in 2017, Raikoke eruption in 2019, Australian wild fires in 2019-2020, and the Hunga Tunga eruption in 2022. Such events not only lead to aerosols and water vapor injection in the stratosphere but can also have some effects on stratospheric dynamics. For instance, some of our team showed that the Australian bushfires created an anticyclonic vortex that persisted in the stratosphere for over 13 weeks. The effect of the Hunga Tunga eruption on water vapor injection and aerosols is shown in the figure above. Just after this massive injection of water vapor, a rapid descend of aerosols occurred due to the cooling effect of water vapour infrared emission while sedimentation was shown to play a secondary role.

Permanent Staff

A. Hertzog, B. Legras, F. Lott, A. Pogdlajen, R. Plougonven

PhD students, postdocs

R. Atlas, V. Bremaud, C. Duchamp, M. Rezig, I. Toghraei