Speaker is Prof.Athanasios Nenes (EPFL/FORTH) and scientific coordinator of CleanCloud.

Abstract:
Much of the predictive uncertainty around human impacts on climate is related to poorly understood and constrained aerosol-cloud interactions. We present an overview of the aerosol-cloud interaction studies carried out in the E. Mediterranean site at Mt. Helmos, Greece during the the Cloud-AerosoL InteractionS in the Helmos background TropOsphere (CALISHTO; Fall 2001 to Winter 2022). A synergy of in-situ, remote sensing and modelling experiments was used to determine the atmospheric state and source of cloud condensation nuclei (CCN) and ice nuclei (IN) for warm and mixed-phased clouds formed at the region. The influences of boundary layer turbulence, vertical aerosol distributions and meteorological conditions on cloud microphysical state (supersaturation, susceptibility) and droplet/ice formation will be discussed. Finally we will focus on the role of secondary ice processes (SIP) for the formation of snow and precipitation in mixed-phase clouds during CALISHTO, and demonstrate the powerful insights that the fusion of modeling, remote sensing and in-situ observations can provide on these highly uncertain processes.