Abstract
Abstract. Many applications require wind gust estimates at very different atmospheric height levels. For example, the renewable energy sector is interested in wind and gust predictions at the hub height of a wind power plant. However, numerical weather prediction models typically only derive estimates for wind gusts at the standard measurement height of 10 m above the land surface. Here, we present a statistical post-processing method to derive a conditional distribution for hourly peak wind speed as a function of height. The conditioning variables are taken from the COSMO-REA6 regional reanalysis. The post-processing method was trained using peak wind speed observations at five vertical levels between 10 and 250 m from the Hamburg Weather Mast. The statistical post-processing method is based on a censored generalized extreme value (cGEV) distribution with non-homogeneous parameters. We use a least absolute shrinkage and selection operator to select the most informative variables. Vertical variations of the cGEV parameters are approximated using Legendre polynomials, such that predictions may be derived at any desired vertical height. Further, the Pickands dependence function is used to assess dependencies between gusts at different heights. The most important predictors are the 10 m gust diagnostic, the barotropic and the baroclinic mode of absolute horizontal wind speed, the mean absolute horizontal wind at 700 hPa, the surface pressure tendency, and the lifted index. Proper scores show improvements of up to 60 % with respect to climatology, especially at higher vertical levels. The post-processing model with a Legendre approximation is able to provide reliable predictions of gusts' statistics at non-observed intermediate levels. The strength of dependency between gusts at different levels is non-homogeneous and strongly modulated by the vertical stability of the atmosphere.
Highlights
Severe wind events are one of the main weather hazards for humans and economies
A steady strong wind is most efficient for the power production, as the power produced at wind plants is proportional to the cube of the horizontal wind speed
For the planning and operation of wind power plants, accurate estimates and forecasts of wind gusts are of great value and are requested near the surface but along their entire vertical extent
Summary
Extreme wind gusts cause damage to buildings, with effects from loose flying objects to uncovering complete roofs. These hazards affect whole forests, especially those with shallow-rooting trees such as spruce – the most used timber in Germany. Wind prediction is becoming more relevant due to the growing demand in renewable energy, especially in wind power generation. The wind energy plant rotors react slowly to fluctuations in wind patterns; they are not able to transform the higher energy of wind gusts into electricity. For the planning and operation of wind power plants, accurate estimates and forecasts of wind gusts are of great value and are requested near the surface but along their entire vertical extent
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