The Impact of Atmospheric Circulation and Surface Roughness on Changes in Maximum Surface Wind Speed: A Preliminary Study over Northern China

Abstract Excessively strong winds can cause serious damage to wind turbines, which can operate only within cut-in and cut-out wind speeds. In this study, we used the observed daily maximum surface wind speed (MWS) to investigate the long-term changes in the MWS as well as the cut-in and cut-out wind speeds and their causes over northern China. The results revealed that the MWS in northern China decreased, with a trend of −0.324 m s −1 per decade. In addition, the number of days with wind speeds greater than the cut-out wind speed decreased by 1.26 days per decade, whereas the number of days with wind speeds less than the cut-in wind speed increased by 1.9 days per decade. Further study revealed that the influence of atmospheric circulation on the MWS is more prominent at the decadal scale than at the interannual scale. A higher degree of urbanization and increased surface roughness led to a lower MWS. The attribution study revealed that the variance contributions of atmospheric circulation and surface roughness to changes in the MWS are 71.64% and 10.75%, respectively, and the trend contributions of these two factors to changes in the MWS are 14.16% and 81.60%, respectively. The increasing surface roughness dominated the decline in the MWS over northern China. Significance Statement With the proposed goals of energy conservation, wind power generation is receiving increasing attention. However, wind turbines do not operate when the wind speed is either below the cut-in wind speed or above the cut-out wind speed. This study reveals that the maximum surface wind speed (MWS) in northern China showed a decreasing trend from 1985 to 2020; the number of days with wind speeds greater than the cut-out wind speed decreased, and the number of days with wind speeds less than the cut-in wind speed slightly increased. Further study revealed that the influence of atmospheric circulation on the MWS is more prominent at the decadal scale than at the interannual scale. The increasing surface roughness dominated the decreasing trend in the MWS.