The field experiment is being planned for summer 2021, based around Svalbard in the Norwegian Arctic. The purpose is to observe Arctic summer-time cyclones and their two-way coupling with sea ice, particularly in the marginal ice zone. We will be operating the British Antarctic Survey Twin Otter aircraft from Longyearbyen (Svalbard) flying mainly at low levels within the atmospheric surface layer, above the ocean and as much as possible above the marginal ice zone to the north of Svalbard. Our purpose is to measure turbulent fluxes in the atmospheric boundary layer at the same time as remote sensing surface properties beneath, such as ice topography, surface temperature and albedo. Data from the Twin Otter aircraft will be archived at the Centre for Environmental Data Analysis.

The RALI-THINICE team from France and the USA will be flying the SAFIRE ATR42 aircraft in the mid- to upper troposphere (typically around 7 km above sea level) with downward-facing radar and lidar. Their radar has 3 viewing directions and Doppler capability, which means that the wind can be measured and resolved into 3 directional components where there are water drops or ice particles to reflect the radar beams. Combined with the lidar (measuring in the visible range of the EM spectrum) the team can retrieve winds and cloud properties such as ice water content (called the RALI technique). This will enable the team to measure winds and clouds on vertical cross-sections through Arctic cyclones.

The observations from the two aircraft will be complementary, giving a unique exploration of the interior of Arctic cyclones, including winds, temperature, humidity, clouds and turbulence in the atmospheric boundary layer, simultaneous with measurements of the surface properties beneath over sea ice, ocean and the marginal ice zone between.