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The temporal trend of wind speed near the surface over land has been investigated over recent decades. A prevailing trend of decline was found in several studies for most areas in the Northern hemisphere, denoted as terrestrial stilling, with multiple causes being discussed. In this study, we focus on the impact of changes of surface roughness due to changes in land‐use and vegetation cover on this variable for western Europe using the regional climate model RACMO driven by ERA5 reanalysis. We conduct two simulations at climate scale, with and without changes in land‐use and vegetation on a yearly basis. We find that upper level large‐scale circulation slowing down results in declining near surface mean wind speed, and that increases in surface roughness due to changes in land use and vegetation cover play an important role in intensifying this declining trend from our simulations with RACMO. However, the trends inferred from the model simulations and ERA5 are not consistent with trends derived from gridded observations database E‐OBS. This could come from the complexity of integrating in‐situ measurements with uncorrectable inhomogeneity to derive E‐OBS. Plain Language Summary: Wind speed near the surface (10 m above ground) has been declining over many areas in the Northern hemisphere, denoted as terrestrial stilling. This declining trend can be affected by different factors such as increase in surface roughness due to land‐use and vegetation cover changes, large‐scale circulation changes, anthropogenic aerosols and climate change due to greenhouse gas concentration increase. In this study, we focus on the impact of changes in land‐use and vegetation cover on this variable for western Europe using a regional climate model RACMO. We simulate wind speed using two model setups, with and without changes in land‐use and vegetation on a yearly basis. We find that a slowing down of the upper level large‐scale circulation results in a decline of the near‐surface mean wind speed. In addition, we find that based on the difference between our two simulations with RACMO, increases in surface roughness due to changes in land use and vegetation cover intensify this declining trend in near‐surface mean wind speed. Key Points: Wind speed has been decreasing over a large part of western Europe from the surface to 500 hPa according to ERA5 reanalysisRegional climate model simulations forced by ERA5 can reproduce those large‐scale features of wind speed wellThe increase in surface roughness intensifies those large‐scale decreasing trends of near surface wind speed at regional and local scales [ABSTRACT FROM AUTHOR]

Long‐term variations in maximum gust speeds have been analyzed using wind measurements recorded at St Mary's, Isles of Scilly, UK, and possible drivers of recent changes have been investigated. A rigorous homogenization procedure has been applied to the wind records to remove discontinuities mainly caused by non‐climatic changes. Trends in magnitude of the homogenized annual and monthly maximum gust speeds have been subsequently estimated. A significant (p < 0.10) decreasing trend of −0.102 m s−1/10 years is exhibited by the annual maximum gust speeds over the period 1928–2011, while a non‐significant (p > 0.10) positive trend characterizes the entire period 1928–2020 of wind measurements. A turning point has been detected in the monthly maximum gust speed series in 2012, followed by a trend reversal. Distinctive differences in the gust trend pattern have been observed among the seasons, with increasing trend in summer, and winter gust speeds exhibiting decline in 1969–2011 and strengthening since 2012. Variations in the monthly maximum gust speeds appear closely related to changes in air temperature and latitudinal pressure gradients. Furthermore, the monthly maximum gust speeds show significant correlation with the main oceanic‐atmospheric circulation patterns in the North Atlantic region. A synergistic effect among the phases of the dominant patterns of climate variability appears to explain the observed decline and recovery trends in winter gusts. Summer gust speeds show a positive correlation with the global land‐ocean temperature deviations from the corresponding 1951–1980 base period mean. Key Points: Homogenization of historical gust speeds at St Mary's, Isles of Scilly, has been performed to remove discontinuities caused by non‐climatic changesSummer gust speeds have significantly increased, while winter gust speeds have declined in 1969–2011 and strengthened since 2012Statistically significant correlations are found between monthly maximum gust speeds and main climate indices which might explain the observed variability [ABSTRACT FROM AUTHOR]

Near‐surface seasonal and annual mean wind speed in Switzerland is investigated using homogenized observations, Twentieth Century Reanalysis (20CRv2c) data and raw model output of a 75 member EURO‐COoRdinated Downscaling EXperiment regional climate model (RCM) ensemble for present day and future scenarios. The wind speed observations show a significant decrease in the Alps and on the southern Alpine slopes in the period 1981–2010. However, the 20CRv2c data reveal that the recent trends lie well within the decadal variability over longer time periods and no clear signs of a systematic wind stilling can be found for Switzerland. The ensemble of RCMs shows large biases in the annual mean wind speed over the Jura mountains, and some members also show large biases in the Alps compared to station observations. The spatial distribution of the model biases varies strongly between the RCMs, while the resolution and the driving global model have less impact on the pattern of the model bias. The RCMs are mostly able to represent the seasonality of wind speed on the Plateau but miss important details in complex terrain related to local wind systems. Most models show no significant changes in near‐surface mean wind speed until the end of the 21st century. The model ensemble changes range from a 7% decrease to a 6% increase with an ensemble mean decrease of 1 to 2%. Due to model biases, the scale mismatch between model grid and station observations and the missing representation of local winds in the simulations, the changes need to be interpreted with utmost care. Future assessments might lead to major revisions even for the sign of the projected changes, in particular over complex terrain. [ABSTRACT FROM AUTHOR]