Operational wind plants increase planetary boundary layer height: An observational study

Abstract. As wind energy deployment grows, interactions between wind plants and the surrounding environment become more prevalent. The current investigation seeks to understand these interactions by characterizing the impact of wind plants on the planetary boundary layer height (PBLH), utilizing observations from the American WAKE ExperimeNt (AWAKEN) campaign. Given the ambiguity of the definition of PBLH under stable atmospheric conditions, where the impact of wind plants is expected to be strongest, a comparison of different methods for identifying PBLH is first conducted using data collected by multiple different instruments. Then, using one of these methods that is thermodynamic and another that is turbulence-based, the values of PBLH measured at spatially distributed sites are compared under a range of atmospheric conditions. Both methods show a clear increase in PBLH downstream of a wind plant for stable conditions. These impacts are strongest when the upstream PBLH is shallow (less than 0.25 km), with the thermodynamic method showing a PBLH increase of 33–39 % and the turbulence-based method showing a 141 % increase. At a site 20 km downstream of the wind plant, these effects are no longer observed, suggesting PBLH has recovered. The results of this investigation show that wind plants can modify the surrounding atmosphere, improving understanding of wind plant–atmosphere interaction that is crucial for model development and validation.