The French ATR-42 is a bi turbo-prop aircraft from SAFIRE that has the capability of flying in the lower troposphere (ceiling at about 8 km) with a maximum range (with the MAESTRO payload) of about 1000 km. It will fly a series of legs within the sub-cloud layer, near cloud base and in the mid-troposphere. The legs will be about 200 km long, and will sample shallow and deep convective clouds together with their environment. A particularity of the aircraft instrumentation is that it will include multi-directional remote sensing, including sideways and vertically-pointing lidars and radars that will probe the atmosphere horizontally and vertically, aiming at characterizing the cloud geometry (horizontal and vertical), horizontal distributions of water vapor, temperature, clouds and aerosols, cloud microphysical and optical properties (liquid and ice water content, particle size distribution, scattering phase function), and the three-dimensional wind around the aircraft. The legs below cloud level will aim at characterizing turbulence and coherent structures in the subcloud-layer, the thermodynamic properties of the subcloud-layer, temperature at the sea surface, and radiative fluxes. Given the mean science speed of the aircraft (about 100 m/s) and the endurance expected for the envisioned payload, the ATR-42 will make two to three three-hour flights per day bracketed by the daily nine-hour flight of HALO.
