Developed by BORÉAL SAS, the Boréal unmanned aerial vehicle (UAV) is a fixed-wing platform, weighing less than 25kg and capable of traveling 700 km with a payload of 5 kg. The Boreal has a wingspan of 4.20 meters and has a nominal cruise speed of 100 km h-1 (with a range between 60-130km h-1). The BOREAL is particularly well-suited for probing the marine boundary layer between 40 and 3000 m.asl. The BOREAL system has been used successfully by the Centre National de Recherches Météorologiques (CNRM) during the MIRIAD and RENOVRISK campaigns in the Indian Ocean. The Boréal UAV will make one six-hour flight per flight day coordinating with the other research aircraft (HALO, ATR-42 and the Twin Otter).
The Boréal UAV is launched from a catapult (see picture) and lands on its belly allowing for relatively short take-off and landing operations in the field. It is equipped with a transponder (24-bit S-mode) for integrating flights into international airspace, a radio frequency / satellite communication system for long distance flight. The payload of 5 kg includes sensors to measure air-sea exchanges: multi-hole 3D wind and turbulence probe, particle counter and number size distribution, altimetry radar (wave height), temperature of sea surface, downwelling broadband solar radiation, pressure / temperature / humidity and real-time video. Data from these sensors are available in real-time on the ground station.
|Condensation particle counter||The condensation particle counter measures total aerosol concentrations (NCN) between 0 and 105 cm-3 in the diameter range (dp > 0.01 µm. The condensation particle counter is used to identify new particle formation and pollution aerosol.|
|Optical particle counter||An optical particle counter measures aerosol size distributions (0.3 µm < dp < 3 µm) to measure emissions of primary marine aerosol and confirm mixing in the boundary layer.|
|Multi-hole turbulence probe||The multi-hole turbulence probe extends into the free stream in front of the UAS to measure the three-dimensional wind vectors, boundary layer turbulence and fluxes.|
|Sea surface temperature||The infrared sensor measures sea surface temperature during low altitude legs (< 100 m.asl).|
|Radar altimeter||The radar altimeter is used to measure sea state including wave height, speed and direction. The different types of waves (e.g., swell and wind can also be distinguished).|
|Broadband solar irradiance||The pyranometer measures total hemispherical solar irradiance over spectral range between 0.4 µm and 01.1 µm. The pyranometer will be used to detect clear sky and cloud coverage.|
|State Parameters||These sensors are used to measure temperature, pressure and relative humidity, from which atmospheric parameters including potential temperature, stability, boundary layer height, and lifting condensation level are derived.|
Corrigan, C.E., G.C. Roberts, M.V. Ramana, D. Kim, and V. Ramanathan: Capturing Vertical Profiles of Aerosols and Black Carbon over the Indian Ocean using Autonomous Unmanned Aerial Vehicles, Atmos Chem Phys, 8, 737-747, 2008.
Roberts, G.C., M.V. Ramana, C. Corrigan, D. Kim, and V. Ramanathan: Simultaneous observations of aerosol-cloud-albedo interactions with three stacked unmanned aerial vehicles, PNAS, 105, 7370-7375, 2008.
Sanchez, K.J., G.C. Roberts, R. Calmer, K. Nicoll, E. Hashimshoni, D. Rosenfeld, J. Ovadnevaite, J. Preissler, D. Ceburnis, C. O'Dowd, L.M. Russell, Top-down and bottom-up aerosol–cloud closure: towards understanding sources of uncertainty in deriving cloud shortwave radiative flux, doi.org/10.5194/acp-17-9797-2017, 2017.
Calmer, R., G.C. Roberts, J. Preissler, K.J. Sanchez, S. Derrien, C. O'Dowd, Vertical wind velocity measurements using a five-hole probe with remotely piloted aircraft to study aerosol–cloud interactions, doi.org/10.5194/amt-11-2583-2018, 2018.
Calmer, R., G.C. Roberts, K.J. Sanchez, J. Sciare, K. Sellegri, D. Picard, M. Vrekoussis, M. Pikridas, Aerosol-Cloud Closure Study on Cloud Optical Properties using Remotely Piloted Aircraft Measurements during a BACCHUS Field Campaign in Cyprus, doi.org/10.5194/acp-2019-8, 2019.