Is the Growing Number of Wind farms Connected to Boundary-layer Mixing Characteristics in Northern Oklahoma?

Wind farms are steadily increasing around the world, and they will continue to grow in size and number as efforts shift toward a carbon-neutral future harnessing more renewable energy. Previous studies found wind farms can impact vertical mixing in the atmospheric boundary layer (ABL), which can alter the local climate. In this study, we analyzed ABL properties in northern Oklahoma, where the number of large wind farms has been continuously increasing since 2012. Observations collected during the American WAKE ExperimeNt (AWAKEN) assisted in understanding the implications of wind farms in a location undisturbed by complex terrain or coastal effects. For AWAKEN, we deployed the two Collaborative Lower Atmospheric Mobile Profiling Systems (CLAMPS), each containing kinematic and thermodynamic remote-sensing instruments such as scanning lidars capable of continuous, high-resolution measurements of vertical velocity w. We use CLAMPS lidar w measurements to investigate the influence of wind farms on vertical mixing. The CLAMPS1 trailer collected near-farm observations, while CLAMPS2 collected far-field observations, allowing for comparisons between datasets of differing w characteristics inside and outside the path of wind farms’ likely area of influence. From July 1st to September 28th, 2023, both CLAMPS lidars continuously measured w from roughly 60-4000 m at a 1-second temporal resolution allowing for the computation of mean vertical velocity w and w, a measure of turbulent vertical mixing. Results throughout the campaign show stronger vertical motions at the near-farm site throughout the summer campaign. Different characteristics were observed in the near-surface layer in the upper ABL. The effects close to the surface are thought to be directly related to wind farm influences. Drivers behind the stronger upper-level vertical motions are less clear. As part of an ongoing analysis, characteristics of the nocturnal low-level jet will be added to these site comparisons, given the important role it can play in nocturnal mixing and how wind farm influences may modify it.