全球变化知识资源中心

Using the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR), Japanese 55-year (JRA55), and European Centre for Medium-Range Weather Forecasts Interim (ERA-Interim) reanalysis datasets and station observational data, the variations in near-surface wind speed are analyzed in China. The results show that near-surface wind speeds decreased by approximately -0.109ms(-1)decade(-1) from 1958 to 2015 in China; however, this decreasing trend has not been evident since 2000. The decreasing trend was caused by the weakening of both the zonal (u) and meridional (v) components of wind vectors during all seasons. Weakened v components are closely related to the weakened Siberian High (SH), and the decreasing pressure gradient associated with the SH causes a reduction in the north wind. The reduction in the u component has a limited association with the SH from a nationwide perspective, and the enhanced geopotential height over Northeast Asia plays a non-negligible role in the variability of u and causes a weakening of the prevailing west wind in Northeast China. The results also show that the JRA55 reanalysis dataset can better reflect the changes and spatial distribution of near-surface wind speeds in China than can the NCEP/NCAR and ERA-Interim reanalysis datasets. The correlation coefficient between the wind speed anomalies in the JRA55 and observational datasets is 0.842, which is notably larger than that in the NCEP/NCAR and ERA-Interim reanalysis datasets (0.527 and 0.576, respectively).