The Perdigão field campaigns probed atmospheric flow in and around a double-ridge valley in Portugal equipped with one turbine, collecting data critical for improving fundamental insights into flow in complex terrain as well as methods for quantifying wind resources. While the Perdigão 2015 campaign pioneered coordinated scans from three scanning lidars, Perdigão 2017 included an unprecedented array of instrumentation, including 30 scanning and profiling lidars to map the valley's atmosphere. An array of approximately 50 towers, equipped with sonic anemometers and ranging in height from 10 to 100 m, provided in situ measurements to measure air flow and turbulence. Radiosondes, thermistor arrays, microwave radiometers, and an Atmospheric Emitted Radiance Interferometer (AERI) measure temperature structure. Acoustic measurements, seismographic measurements, and tethered systems measuring high-rate turbulence data also provide unique insights into the numerous flow phenomena observed in the valley. In addition to studying complex terrain effects on the wind resource and wind turbine wakes, the Perdigão data enable insights into interactions between flows of different scales, effects of topographic and diurnal thermal forcing, valley/slope boundary layers, and recirculations within the valley.

This special issue is open for all submissions within its scope, addressing measurements, simulations, and case studies from both Perdigão field campaigns.