Nocturnal Observations of Thermodynamic and Kinematic Properties in a Wind Turbine Array Boundary Layer Using an Instrumented Unmanned Aerial System

Observation, simulation, and modeling have shown that wind farms have an impact on the near-surface atmospheric boundary layer as turbulent wakes generated by the turbines enhance vertical mixing. These changes alter downstream atmospheric properties. With a large portion of wind farms hosted within an agricultural context, changes to the environment can potentially have secondary impacts such as to the productivity of crops. The authors, amongst others, have demonstrated changes to relative humidity and temperature within the wind turbine array boundary layer during daylight observations made by small unmanned aerial systems (sUAS). The obtainment of permission to fly at night and higher altitudes, along with the enhancement of the sUAS instrumentation suite with fast-response 3D sonic anemometers, enabled observations during overnight hours and at altitudes above the top turbine tip height. This talk details observed changes to thermodynamic and kinematic properties during an overnight field campaign undertaken during the summer of 2019 around a utility-scale wind turbine located within a variety of crops