Little is known regarding the radiative effects of clouds and their microphysical structure in Polar regions, causing climate models to suffer from large uncertainties in the representation of Polar clouds and their effects. In addition, increasing interest on Polar regions and their impact on lower latitudes led the WMO to establish the Polar Prediction Project and the Year Of Polar Prediction (YOPP).

The CLouds And Radiation in the Arctic and Antarctica (CLARA2) is a bi-Polar project aiming at investigating the optical and physical properties of clouds, quantifying their effects on the surface and atmospheric radiative budget. Concurrently, CLARA2 will contribute to the YOPP 2020 Arctic Special Observing Period with intensive measurements of the atmospheric vertical structure by means of a microwave profiler and daily radiosoundings.

The project proposes measurements campaigns at two coastal sites: Thule Air Base, Greenland, and M. Zucchelli station, Antarctica, employing the same set of instruments and methods. The campaigns will involve ground-based instrumentation operating in the VIS, IR and MW regions, which will provide a comprehensive dataset of atmospheric and cloud parameters. The observations at the two sites will be used as input for radiative transfer calculations, constrained by surface and satellite observations, which will allow the investigation of the role played by different conditions of background condensation nuclei, humidity, and synoptic variability on cloud properties.

The proposal includes a strong collaboration with foreign institutions (Univ. of Cologne and PWD/PMOD) and international projects (MOSAiC, ICECAP and AC3), whose PI’s enthusiastically endorsed this project. CLARA2 will strengthen the Italian role within the international Polar community by producing an uncommon database for atmospheric research. This project will also enhance the cloud observational capabilities at MZS with the installation of a microwave profiler.