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Title: The Pilatus unmanned aircraft system for lower atmospheric research

This study presents details of the University of Colorado (CU) “Pilatus” unmanned research aircraft, assembled to provide measurements of aerosols, radiation and thermodynamics in the lower troposphere. This aircraft has a wingspan of 3.2 m and a maximum take-off weight of 25 kg, and it is powered by an electric motor to reduce engine exhaust and concerns about carburetor icing. It carries instrumentation to make measurements of broadband up- and downwelling shortwave and longwave radiation, aerosol particle size distribution, atmospheric temperature, relative humidity and pressure and to collect video of flights for subsequent analysis of atmospheric conditions during flight. In order to make the shortwave radiation measurements, care was taken to carefully position a high-quality compact inertial measurement unit (IMU) and characterize the attitude of the aircraft and its orientation to the upward-looking radiation sensor. Using measurements from both of these sensors, a correction is applied to the raw radiometer measurements to correct for aircraft attitude and sensor tilt relative to the sun. The data acquisition system was designed from scratch based on a set of key driving requirements to accommodate the variety of sensors deployed. Initial test flights completed in Colorado provide promising results with measurements from the radiationmore » sensors agreeing with those from a nearby surface site. Additionally, estimates of surface albedo from onboard sensors were consistent with local surface conditions, including melting snow and bright runway surface. Aerosol size distributions collected are internally consistent and have previously been shown to agree well with larger, surface-based instrumentation. Finally the atmospheric state measurements evolve as expected, with the near-surface atmosphere warming over time as the day goes on, and the atmospheric relative humidity decreasing with increased temperature. No directional bias on measured temperature, as might be expected due to uneven heating of the sensor housing over the course of a racetrack pattern, was detected. The results from these flights indicate that the CU Pilatus platform is capable of performing research-grade lower tropospheric measurement missions.« less
 [1] ;  [2] ;  [2] ;  [2] ;  [2] ;  [3] ;  [2] ;  [2] ;  [2] ;  [1] ;  [4] ;  [2] ;  [5] ;  [6]
  1. Univ. of Colorado, Boulder, CO (United States); National Oceanographic and Atmospheric Administration, Boulder, CO (United States)
  2. Univ. of Colorado, Boulder, CO (United States)
  3. National Oceanographic and Atmospheric Administration, Boulder, CO (United States)
  4. National Aeronautics and Space Administration, Wallops Island, VA (United States)
  5. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  6. National Center for Atmospheric Research, Boulder, CO (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 1867-8548; KP1704010
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Atmospheric Measurement Techniques (Online)
Additional Journal Information:
Journal Name: Atmospheric Measurement Techniques (Online); Journal Volume: 9; Journal Issue: 4; Journal ID: ISSN 1867-8548
European Geosciences Union
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
Sponsoring Org:
Country of Publication:
United States