Does the wind turbine wake follow the topography? A multi-lidar study in complex terrain

The wake of a single wind turbine in complex terrain is analysed using measurements from lidars. A particular focus of this analysis is the wake deficit and propagation. Six scanning lidars (three short-range and three long-range WindScanners) were deployed during the Perdigão 2015 measurement campaign, which took place at a double-ridge site in Portugal. Several scanning scenarios, including triple- and dual-Doppler scans, were designed to capture the wind turbine wake of a 2 inline-formulaMW turbine located on one of the ridges. Different wake displacements are categorized according to the time of the day. The results show a strong dependence of the vertical wake propagation on the atmospheric stability. When an atmospheric wave is observed under stable conditions, the wake follows the terrain down the ridge with a maximum inclination of inline-formula $M2inlinescrollmathml-\mathrm{normal\; 28}{}^{\circ }$ 26pt11ptsvg-formulamathimg0dfe92f7417d33bf0b6d9f9e228b59f3 wes-3-681-2018-ie00001.svg26pt11ptwes-3-681-2018-ie00001.png . During unstable conditions, the wake is advected upwards by up to 29inline-formula^∘ above the horizontal plane.