EOL Seminar: Turbulence in complex terrain: insights from the Perdigão field campaign

Tuesday, February 25, 2020 - 10:30 to 11:30
Contact Name: 
Melissa Ward
Contact Email: 
Contact Phone: 
(303) 497-8713

Dr. Julie K. Lundquist

University of Colorado, Boulder, United States

In 2017, after a decade of preparation, a consortium of US and European and U.S. research groups conducted a field campaign 1 May–15 June 2017 in the Vale do Cobrão in central Portugal to explore microscale processes in complex terrain. This valley is nestled within a parallel double ridge near the town of Perdigão. Further, an isolated 2-MW wind turbine (rotor diameter 82 m) is located on one ridge. Typical wind directions measured at the ridgetops are normal to the ridges, suggesting a simple yet natural setting for studies of flow and turbulence in complex terrain, as well as interactions with the wind turbine wake.

Over twenty-five remote sensing instruments (lidars, sodars, radars, radiometers, including 8 scanning lidars) and 45+ meteorological towers were deployed in a 4km x 4km region to closely document flow over, through, and around the Vale do Cobrão. Profiling lidars, scanning lidars and airborne hotwire anemometers provide new insights into the onset and decay of turbulence within the valley and above the ridges, especially occurrences of topographically-driven flow reversal. Lidar analysis coupled with radiosonde profiles document the conditions leading to lee wave generation across the valley. Routine scanning lidar transects across the valley document the occurrences of flow recirculation. Other scanning lidar measurements document the behaviour of the wind turbine wake.

The density of measurements offers new insights into the variability of flow in complex terrain. These insights are both applied, such as new rules of thumb for wind turbine deployment in complex terrain, and fundamental, regarding improved methods for the parameterization of turbulence in complex terrain. Current and ongoing data analysis, as well as large-eddy simulations of specific case studies, will be highlighted.