26. Impact of Aerosol Properties on Cloud and Precipitation Formation

Clouds droplets are directly dependent on aerosols that are present in the atmosphere and on their probabilities to act as cloud condensation nuclei (CCN). So, it is necessary to study aerosols distributions native to different air masses in order to understand cloud droplets distributions. Sensitivity tests, using WRF‐chem (Weather Research and Forecast), should allow an improvement in the knowledge of aerosol properties and their impacts on cloud droplets and precipitation. From this perspective, simulations for various air masses are simulated with WRF-chem using RADM2 (Stockwell et al., J. Geophys Res, 95:16343–16367, 1990) chemical mechanism associated with MADE/SORGAM aerosol module (Ackermann et al., Atmos Environ, 32(17):2981–2999, 1998) which dissociates aerosols into three modes: Aitken, accumulation and coarse modes. Furthermore, comparisons are presented between model outputs and observation data from the puy de Dôme site. This site, part of the ACTRIS network, has been equipped with many probes in order to characterize the physical, chemical and optical properties of aerosol particles, to quantify gases (O₃, CO, CO₂, NO, NO₂, …), to measure radiation and to document typical meteorological parameters and in particular cloud parameters (cloud water content, cloud droplet concentrations and mean radius).