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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union
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Volume 11, issue 9 | Copyright
Atmos. Meas. Tech., 11, 5025-5048, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 05 Sep 2018

Research article | 05 Sep 2018

Development and characterization of a high-efficiency, aircraft-based axial cyclone cloud water collector

Ewan Crosbie1,2, Matthew D. Brown1,3, Michael Shook1, Luke Ziemba1, Richard H. Moore1, Taylor Shingler1,2, Edward Winstead1,2, K. Lee Thornhill1,2, Claire Robinson1,2, Alexander B. MacDonald4, Hossein Dadashazar4, Armin Sorooshian4,5, Andreas Beyersdorf6, Alexis Eugene7, Jeffrey Collett Jr.8, Derek Straub9, and Bruce Anderson1 Ewan Crosbie et al.
  • 1NASA Langley Research Center, Hampton, VA 23666, USA
  • 2Science Systems and Applications, Inc. Hampton, VA 23666, USA
  • 3Universities Space Research Association, Columbia, MD 21046, USA
  • 4Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ 85721, USA
  • 5Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ 85721, USA
  • 6Department of Chemistry and Biochemistry, California State University, San Bernardino, CA 92407, USA
  • 7Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
  • 8Atmospheric Science Department, Colorado State University, Fort Collins, CO 80523, USA
  • 9Department of Earth and Environmental Sciences, Susquehanna University, Selinsgrove, PA 17870, USA

Abstract. A new aircraft-mounted probe for collecting samples of cloud water has been designed, fabricated, and extensively tested. Following previous designs, the probe uses inertial separation to remove cloud droplets from the airstream, which are subsequently collected and stored for offline analysis. We report details of the design, operation, and modelled and measured probe performance.

Computational fluid dynamics (CFD) was used to understand the flow patterns around the complex interior geometrical features that were optimized to ensure efficient droplet capture. CFD simulations coupled with particle tracking and multiphase surface transport modelling provide detailed estimates of the probe performance across the entire range of flight operating conditions and sampling scenarios.

Physical operation of the probe was tested on a Lockheed C-130 Hercules (fuselage mounted) and de Havilland Twin Otter (wing pylon mounted) during three airborne field campaigns. During C-130 flights on the final field campaign, the probe reflected the most developed version of the design and a median cloud water collection rate of 4.5mLmin−1 was achieved. This allowed samples to be collected over 1–2min under optimal cloud conditions. Flights on the Twin Otter featured an inter-comparison of the new probe with a slotted-rod collector, which has an extensive airborne campaign legacy. Comparison of trace species concentrations showed good agreement between collection techniques, with absolute concentrations of most major ions agreeing within 30%, over a range of several orders of magnitude.

Publications Copernicus
Short summary
A new aircraft-mounted probe for collecting samples of cloud water has been designed, fabricated, and extensively tested. Cloud drop composition provides valuable insight into atmospheric processes, but separating liquid samples from the airstream in a controlled way at flight speeds has proven difficult. The features of the design have been analysed with detailed numerical flow simulations and the new probe has demonstrated improved efficiency and performance through extensive flight testing.
A new aircraft-mounted probe for collecting samples of cloud water has been designed,...