(AC)³ scientists from TROPOS and LIM started the first measurement period of vertical profiling of the cloudy Arctic boundary layer with the tethered balloon system BELUGA over Ny-Ålesund (Svalbard). Their tragets are: Clouds, Aerosol, Radiation, and Turbulence.

The goal of this project is to collect vertical profile data in the the cloud-free and cloudy atmospheric boundary layer. For this purpose, the tethered balloon system BELUGA with combined instrument payloads for thermodynamic, turbulence, radiation, as well as cloud and aerosol in-situ measurements will be deployed at the AWIPEV station. A second mesurement period in March-May 2022 will be combined with the HALO-(AC)³ campaign.

The cloudy Arctic boundary layer (ABL) is characterized by a complex vertical stratification with frequently decoupling from the surface. Clouds strongly modulate the exchange of latent heat and cause significant radiative effects; both heat and radiative energy fluxes are major drivers for turbulent mixing. Models have difficulties in representing these processes and often fail to realistically describe the development of the cloudy ABL. Therefore, we propose to conduct detailed measurements of the temporal evolution of the Arctic ABL in contrasting seasons (fall and the transition to Polar night, spring and the transition into the melting season in early summer) using unique thermodynamic, turbulence, radiation, as well as cloud and aerosol instrumental payloads carried by a tethered balloon at the AWIPEV station in in Ny-Ålesund. The general goal of this project is to collect vertical profile data of the temporal evolution of the cloud-free and cloudy ABL. For this purpose, the tethered balloon system BELUGA with combined instrument payloads for thermodynamic, turbulence, radiation, as well as cloud and aerosol in-situ measurements shall be deployed at the AWIPEV station in Ny-Ålesund in different seasons. Firstly, the data collection aims at the statistical characterization of vertical profiles to quantify daily and seasonal differences. The second goal is to evaluate the capability of dynamic and radiative transfer models to realistically reproduce the transition from cloud-free to cloudy conditions and the following cloud evolution.