Future projections of the near-surface wind speed over eastern China based on CMIP5 datasets

The slowdown of the near-surface wind speed (SWS) has been extensively reported in China, but future projections of the SWS are rare. In this study, the wind speeds of Coupled Model Intercomparison Project phase 5 (CMIP5) datasets were compared with observations over Eastern China, and the possible influences of increasing CO2 emissions on the changes in SWS were investigated. The results show that although the CMIP5 models reproduced the spatial pattern of SWSs, they underestimated the long-term reduction of the SWSs during the historical period from 1979 to 2005. Compared to the traditional arithmetic mean ensemble method (AMEM), the relative error in the weighted mean ensemble method (WMEM) decreased by 8.5%, and the root-mean square error decreased by 0.14 m s(-1). Compared to the WMEM, a smaller error was obtained for the results of the statistical downscaling model (SDM), which was established based on the principal component analysis and the stepwise regression equation and used the ensemble meteorological variables as predictor. Based on the SDM, CO2 emission increases could induce the decreases of SWSs in the future, with the significantly decreasing trends of - 0.007 and - 0.002 m s(-1) decade(-1) under the RCP8.5 and RCP4.5 emission scenarios, respectively. The probability of annual mean SWSs exceeding 2.37 m s(-1) decreased by 12.1% under RCP8.5 relative to RCP4.5. Furthermore, the annual mean SWSs could show a weak strengthening over the next 20 years.