How long can constant wind speed periods last in the turbulent atmospheric boundary layer?

Abstract

The statistical characteristics of periods of constant wind speed in the atmospheric turbulent wind are investigated. Our hypothesis is that specific circumstances of these structures in the wind may lead to not yet identified phenomena on an operating wind turbine. Therefore, the characterisation in terms of their lengths, probability of occurrence and extreme events is the focus of this study. Two data sets from atmospheric wind are analysed. Our findings reveal that the statistics of constant wind speed periods depends firstly, on the precise definition of wind speed thresholds and secondly, on the degree of turbulence. Additionally, a comparison to wind time series generated with a standard model suggests that these structures might not be properly reproduced by standard wind field models.