Assimilation of a Coordinated Fleet of Uncrewed Aircraft System Observations in Complex Terrain: EnKF System Design and Preliminary Assessment

Anders Jensen, James Pinto, Sean Bailey, Ryan Sobash, Gijs de Boer, Adam Houston, Phillip Chilson, Tyler Bell, Glen Romine, Suzanne Smith, Dale Lawrence, Cory Dixon, Julie Lundquist, Jamey Jacob, Jack Elston, Sean Waugh, Matthias Steiner

Research output: Contribution to journalArticlepeer-review

19 Scopus Citations


Uncrewed aircraft system (UAS) observations collected during the 2018 Lower Atmospheric Process Studies at Elevation—a Remotely Piloted Aircraft Team Experiment (LAPSE-RATE) field campaign were assimilated into a high-resolution configuration of the Weather Research and Forecasting Model using an ensemble Kalman filter. The benefit of UAS observations was assessed for a terrain-driven (drainage and upvalley) flow event that occurred within Colorado’s San Luis Valley (SLV) using independent observations. The analysis and prediction of the strength, depth, and horizontal extent of drainage flow from the Saguache Canyon and the subsequent transition to upvalley and up-canyon flow were improved relative to that obtained both without data assimilation (benchmark) and when only surface observations were assimilated. Assimilation of UAS observations greatly improved the analyses of vertical variations in temperature, relative humidity, and winds at multiple locations in the northern portion of the SLV, with reductions in both bias and the root-mean-square error of roughly 40% for each variable relative to the benchmark run. Despite these noted improvements, some biases remain that were tied to measurement error and/or the impact of the boundary layer parameterization on vertically spreading the observations, both of which require further exploration. The results presented here highlight how observations obtained with a fleet of profiling UAS improve limited-area, high-resolution analyses and short-term forecasts in complex terrain.
Original languageAmerican English
Pages (from-to)1459-1480
Number of pages22
JournalMonthly Weather Review
Issue number5
StatePublished - 2021

NREL Publication Number

  • NREL/JA-5000-78410


  • complex terrain
  • unmanned aircraft system
  • weather research and forecasting


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