Raphael Lebrun defended on June 23, 2023 at Sorbonne University as part of the ANR MCG-Rad project. The first part of his work concerns the modeling of vertical cloud cover, which has a very strong influence on the calculation of solar flux at the top of the atmosphere. It has been shown that an exponential-random overlap provides a very good representation of cloud properties, both geometric and radiative, even from a coarsely resolved vertical cloud profile. This modeling was then coupled with a Monte Carlo radiative transfer calculation (RadForce), using a line-by-line approach for the various atmospheric gases. This made it possible to carry out both benchmark calculations and original analyses: estimation of the emission altitude of each component present in the atmosphere, new estimates of the radiative forcing due to each of the greenhouse gases, the impact accounting for vertical cloud cover, etc.

On November 20, 2023, Di Wang defended her thesis in co-supervision with Yunnan University in China. Di studied the isotopic composition of water vapor. This is the relative proportion of different types of water molecules in steam. Di first measured the distribution of isotopic composition in China by driving an instrumented car over 20,000 km. She then measured this isotopic composition at altitudes of up to 11km using instrumented drones she developed herself. This work has applications for reconstructing past climates and understanding the water cycle in Tibet.

Khadija Arjdal defended her thesis on December 20, 2023 at University Mohamed 6 Polytechnic (UM6P) in Morocco. Khadija’s thesis was co-supervised by UM6P and LMD-X, and had a dual objective: 1/ to evaluate and improve the representation of physical processes governing surface climate and water and energy balances in the Moroccan agricultural plains within the LMDZ model and; 2/ assess the sensitivity of climate projections over the Moroccan plains to the representation of processes at the surface-atmosphere interface. By running LMDZ simulations on a refined grid over Morocco and using in situ data, Khadija was able to characterize the model’s ability to reproduce surface climate and identify certain model biases. Khadija was also able to make an initial assessment of the sensitivity of climate change on the Moroccan plains to the maintenance and cessation of field irrigation.

Saloua Balhane defended on December 21, 2023 at University Mohamed 6 Polytechnic (UM6P) in Morocco. Saloua’s thesis was co-supervised by UM6P and LMD. A first achievement of the thesis was to set up a global configuration of LMDZOR with a regionally refined grid preserving the coherence between the large scale and the regional scale. This is essential for Morocco’s climate, where water resources are largely controlled by large-scale processes. Saloua also relied on an online bias correction approach of the dynamics in order to avoid the large-scale biases present in all climate models. After grid refinement, it showed that precipitation and temperature compared favorably with observations, and that moisture transport was improved after online bias correction. Secondly, with the configuration in place and thanks to a specific protocol, Saloua was able to analyze the climate change signal over Morocco for a global warming level of 3K, as well as its sensitivity to uncertainties in the SST patterns projected by different climate models.