Shallow Katabatic Flow in a Complex Valley: An Observational Case Study Leveraging Uncrewed Aircraft Systems

Sean C.C. Bailey, Suzanne Weaver Smith, Michael P. Sama, Loiy Al-Ghussain, Gijs de Boer

Research output: Contribution to journalArticlepeer-review


Multiple fixed-wing and multirotor uncrewed aircraft systems were deployed to measure the early morning katabatic flow along a valley as part of the lower atmosphere profiling studies at elevation a remotely-piloted aircraft team experiment (LAPSE-RATE) campaign. The valley’s topography was that of a narrow canyon emerging into a broader shallow-sloped valley, allowing for an assessment of the suitability of one-dimensional approximations for the broad, flat part of the valley. The one-dimensional integral model predicts growth in the katabatic layer with downslope distance, which was not observed in the broader portions of the valley. Instead, observations revealed thinning of the katabatic layer at the valley centreline, coinciding with oscillatory behavior with a period between 30 and 60 min. These features were attributed to strong asymmetry and three-dimensional features initiating in the narrow part of the valley. These features produced initial conditions upstream of the broad slope flow that were not captured by the one-dimensional model.

Original languageEnglish
Pages (from-to)399-422
Number of pages24
JournalBoundary-Layer Meteorology
Issue number2
StatePublished - Feb 2023

Bibliographical note

Funding Information:
This work was supported by the US National Science Foundation through Award No. CBET-1351411 and by Award No. 1539070, Collaboration Leading Operational UAS Development for Meteorology and Atmospheric Physics (CLOUDMAP). Additional support was provided by the US National Science Foundation (AGS 1807199), US Department of Energy (DE-SC0018985), and the NOAA Physical Sciences Laboratory. The authors would also like to acknowledge Dr. Julie Lundquist and her students Camden Plunkett and Patrick Murphy from University of Colorado Boulder who collected and provided the lidar data used in this study.

Publisher Copyright:
© 2023, The Author(s), under exclusive licence to Springer Nature B.V.


  • Cold-air drainage
  • Katabatic flow
  • Topographic impact
  • Uncrewed aircraft systems (UAS)
  • Valley flows

ASJC Scopus subject areas

  • Atmospheric Science


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