Uncertainties of extreme winds, spectra, and coherences

The uncertainty on the the 50-year storm can be estimated from two widely used methods: the peak over threshold and the maximum model. Long records of wind speeds are usually but not always in agreement with the basic model assumptions. At moderate to high frequencies there is a good agreement among researchers on spectral shapes over homogeneous terrain assuming neutral atmospheric stability. Neutral stability at high wind speeds is a rule with exceptions and despite of high wind speeds an example from the Great Belt Coherence Experiment shows greatly reduced turbulence levels. At low frequencies there is still some discrepancies among model spectra. Due to modeling work based on the Great Belt Coherence Experiment the coherences are well predicted once the spectra are known. Strong wind turbulence in inhomogeneous terrain, which is often the setting of bridges, is an area of active research.