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

Abstract

Assessing change in daily maximum wind speed and its likely causes is crucial for many applications such as wind power generation and wind disaster risk governance. Multidecadal variability of observed near-surface daily maximum wind speed (DMWS) from 778 stations over China is analyzed for 1975-2016. A robust homogenization protocol using the R package Climatol was applied to the DMWS observations. The homogenized dataset displayed a significant (p < 0.05) declining trend of -0.038 m s(-1) decade(-1) for all China annually, with decreases in winter (-0.355 m s(-1) decade(-1), p < 0.05) and autumn (-0.108 m s(-1) decade(-1); p < 0.05) and increases in summer (+0.272 m s(-1) decade(-1), p < 0.05) along with a weak recovery in spring (+0.032 m s(-1) decade(-1); p > 0.10); that is, DMWS declined during the cold semester (October-March) and increased during the warm semester (April-September). Correlation analysis of the Arctic Oscillation, the Southern Oscillation, and the west Pacific modes exhibited significant correlation with DMWS variability, unveiling their complementarity in modulating DMWS. Further, we explored potential physical processes relating to the atmospheric circulation changes and their impacts on DMWS and found that 1) overall weakened horizontal airflow [large-scale mean horizontal pressure gradient (from -0.24 to +0.02 hPa decade(-1)) and geostrophic wind speed (from -0.6 to +0.6 m s(-1) decade(-1))], 2) widely decreased atmospheric vertical momentum transport [atmospheric stratification thermal instability (from -3 to +1.5 decade(-1)) and vertical wind shear (from -0.4 to +0.2 m s(-1) decade(-1))], and 3) decreased extratropical cyclones frequency (from -0.3 to 0 month decade(-1)) are likely causes of DMWS change.