The variability of maximum wind gusts in the Czech Republic between 1961 and 2014

Abstract

This contribution employs instrumental records to analyse the temporal and spatial variability of monthly, seasonal and annual maximum wind gusts (MWGs) in the Czech Republic. The development of an observation network capable of measuring wind gusts, the possible technical weaknesses of wind measurements and problems with establishing homogeneity in wind‐gust data are described. For the 1961–2014 period, quality‐checked data from 19 synoptic stations of the Czech Hydrometeorological Institute throughout the territory of the Czech Republic are examined, divided into three altitudinal groups. In terms of the spatial variability of MWGs, correlation coefficients between stations decrease more strongly in relation to station distance rather than altitude. Spatial correlations are better expressed (by higher correlation coefficients) in the winter half‐year than in the summer half‐year. Linear trends in monthly, seasonal and annual MWGs for the 19 synoptic stations, for their three altitudinal groups, and for the entire Czech Republic show statistically significant decreases (deepest in November and autumn), with the exception of spring (for stations above 300 m) and summer. The 10 highest MWG events of all are selected. The spatial distribution of wind gusts for two prominent windstorms, Kyrill (18–19 January 2007) and Emma (1–2 March 2008), are presented. Changes in MWGs series are compared with fluctuations in atmospheric circulation responding to the North Atlantic Oscillation. Decreasing MWG trends are discussed with respect to diminishing storminess and surface wind speeds (wind stilling) recorded during recent decades in Europe, as well as over other continents.

An approach to homogenize daily peak wind gusts: An application to the Australian series

“…The same for the NCEP/NCAR reanalysis but using the mean wind speed (i.e., with lower values compared to DPWG) quantified (Gubler et al, 2017). For instance, for maximum wind gusts, Brázdil et al (2017) stated that spatial correlation coefficients between stations decrease more strongly in relation to station distance rather than elevation and are higher (i.e., better) in winter than in summer, although the seasonal results are specific to their study area (the Czech Republic) and could not be automatically assumed to apply in for example, tropical or subtropical climate. For Australia, these factors come into play.…”

Variability of Daily Maximum Wind Speed across China, 1975–2016: An Examination of Likely Causes

“…Due to the skewed and possibly changing distribution of wind speed, there is no consensus regarding the trends in wind extremes relative to the mean, and the state of scientific knowledge regarding changes in extreme wind from anemometer observations on multidecadal time scales is currently inconclusive (Azorin-Molina et al 2016;their Table 1). For instance, decreasing trends in wind speed extremes were reported in continental Europe [e.g., the Netherlands (Cusack 2013), Spain and Portugal (Azorin-Molina et al 2016), and the Czech Republic (Brázdil et al 2017)] and are broadly in agreement with stilling, whereas increasing wind speed extremes trends were documented in Japan (Fujii 2007), the United States (Klink 2015), and South Africa (Kruger et al 2010). These findings point to more complicated features of extreme wind speed (e.g., DMWS) changes, which are both spatial and temporally nuanced, and calls for more careful interpretation and deeper understanding of its driving processes in more regions (e.g., China).…”

Differences in wind speeds according to measured and homogenized series in the Czech Republic, 1961–2015

“…This has also been demonstrated in many papers from Europe (as well as the European studies cited in McVicar et al, see, for example, Péliné Németh et al, ; ; Azorin‐Molina et al, ; ; ; Romanić et al, ; Minola et al, ; Laapas and Venäläinen, ; Kohler et al, ). It is also well‐documented for the Czech Republic, based on homogenized wind speed series from 23 stations in 1961–2005 (Brázdil et al, ) and from 119 stations in 1961–2015 (Brázdil et al, ), as well as maximum daily wind gust series of 19 synoptic stations (only quality checked) in 1961–2014 (Brázdil et al, ). The basic results of the current study presented in Table and Figures confirm the existence of stilling, expressed as statistically significant decreasing linear trends in 1961–2015 over the territory of the Czech Republic, independently by the use of both directly‐measured and homogenized data.…”

“…However, difficulties with wind speed homogenisation have meant that the majority of papers addressing wind speeds/gusts are based on only measured (raw) data (Tuller, ; McVicar et al, ; Pryor et al, ; Dadaser‐Celik and Cengiz, ; Brázdil et al, ). In terms of long‐term wind speed trends, such homogenisation may be replaced by calculation of “storminess” from re‐analyses (e.g., the 20th‐century Reanalysis, as in Brönnimann et al, ; Krueger et al, ; Welker and Martius, ), or from geostrophic wind using pressure data (e.g., Alexandersson et al, ; Bärring and von Storch, ; Matulla et al, ; ; Feser et al, ).…”