The Cloud-AerosoL InteractionS measurement campaign in the Helmos background TropOsphere (CALISHTO) is taking place in the next two months (October-November 2021) in the context of PANACEA infrastructure and the ERC program PyroTRACH. Organizers of this campaign are NCSR Demokritos (K. Eleftheriadis), NTUA (A. Papagiannis) and CSTACC-FORTH / EPFL (A. Nenes). The campaign takes place in the area of Mount Helmos, at the HAC2 station, a member of the network of PANACEA, ACTRIS network and the Global Atmospheric Watch (GAW) of the World Meteorological Organization (WMO). The main goal of the CALISHTO campaign is to study the interaction of aerosols with the orographic clouds of the area. This is achieved through a series of observations / measurements that fully characterize the dynamics of the gas masses, the chemical composition, the properties and the origin of the aerosols, as well as the microphysical, macrophysical and visual characteristics of the clouds in the area. The combination of these observations with an integrated set of computational models will give a comprehensive picture of the dynamic and microphysical mechanisms responsible for the formation of droplets, ice crystals and precipitation in orographic clouds.

A summary of the campaign is provided in the attached presentation, while more information is provided on the website of CALISHTO (https://calishto.panacea-ri.gr/) as well as news about the campaign on Twitter of Helmos (https://twitter.com/MtHelmosSite), the ERC PyroTRACH project (https://twitter.com/pyrotrach), the LAPI lab at EPFL (https://twitter.com/LAPI_epfl) and the CSTACC center at FORTH/ICE-HT (https://twitter.com/cstacc). The participation of the Greek and international scientific community is already significant and the organizers are very grateful for this warm support. There is an open invitation for additional teams to participate for any complementary measurements or analyses. Please contact the organizers for any information, omission or to express interest to participate.