Origin and transport of the moisture feeding the Mediterranean Heavy Precipitating Events : characterization and mesoscale assimilation of infrared satellite radiances.

This PhD work aimed at improving the understanding and forecasting of Mediterranean Heavy Precipitating Events (HPEs). This purpose was pursued focusing on two main issues. Firstly, we addressed the question of the origin and transport of the moisture feeding the heavy precipitating systems. Based on a set of 10 HPEs, several moisture sources were identified and their contribution was characterized. The main trajectories of the moisture transport from these remote sources and over the Mediterranean Sea were determined. The second issue investigated in this work is about the improvement of the description in convective-scale numerical weather prediction models of the moisture supply to HPEs. More realistic observation operators were designed for the assimilation of infrared satellite radiances. They improved the simulation of model-equivalent radiances in the water vapor spectral band by filtering out the fine-scale humidity gradients having a smaller size than the observation resolution.