Abstract
This report presents a comprehensive methodology for generating long, spatially coherent turbulent wind time series for offshore wind farm simulations by bridging mesoscale and microscale dynamics. The work was conducted within the EU/HEU WILLOW project to support smart curtailment strategies and fatigue analysis during curtailed operation. The approach integrates hindcast mesoscale data from the NORA3 model with the spectral turbulence model from Cheynet et al. (2018), implemented in the in-house software FLAggTurb using a novel splicing technique. The suitability of NORA3 as forcing for the friction velocity and atmospheric stability was verified against high-frequency measurements at FINO1 and shows good agreement for the friction velocity but an overestimation of instability due to discrepancies in the sensible heat flux. FLAggTurb was verified for spectral consistency, demonstrating robust performance across 21,955 simulations. Two-year-long time series were generated for validation against observations at FINO1 and Ekofisk, showing good mean wind statistics and spectral representation. Strong agreement was observed under stable and neutral conditions, while challenges in unstable regimes and the applicability of Monin–Obukhov Similarity Theory for extended periods were emphasized. Finally, the WindGen/FarmStreamV2 orchestration tool was developed to automate largescale simulation workflows.