Changes Of Wind Energy (speed)over China Under Global Warming And Its Impacts Factors

Based on the observation and reanalysis datasets,the temporal and spatial distributions and variation characteristics of near-surface wind speed over China during 1979 to 2013 were investigated.The reproduce abilities of reanalysis were also evaluated.The interannual varation of summer wind energy and the influence factors of interannual varation over China were analyzed based on the observation and reanalysis dataset.Then,the effect of global warming and land use changes on the near-surface wind speed were evaluated quantitatively.Finally,the future changes of wind energy under 1.5?,2.0?,3.0?,and 4.0? warming targets over China were analyzed based on the outputs of CMIP5 models.The main conclusions are summarized as follows.(1)The near-surface wind speed over Inner Mongolia,Xinjiang and Tibet Plateau is larger than that over Sichuan Basin.The near-surface wind speed is large in spring and small in winter over China.During 1979-2011,the near-suface wind speed showed a significant decreasing trend over China.The interannual varations of near-surface wind speed is large in northern China and Tibet Plateau,while the other regions were relatively small.The reanalysis datasets could reasonally reproduce the climate steate and interannual variations of near-surface wind speed,but the ability of reproducing the annual cycle and linear trend of near-surface wind speed is poor.All reanalysis datasets failed to reproduce the near-surface wind speed in winter.MERRA shows the relatively highest skill in terms of the climatology and linear trend.(2)The summer mean wind power density(WPD)show robust interannual variations over China based on the observation and reanalysis datasets.Encouraging results are seen for all reanalysis datasets,with the MERRA and ERA-Interim datasets showing the best performance.The interannual variation of summer mean wind energy is mainly affected by El Ni?o.During El Ni?o decaying year summers,the WPD over south of the Yangtze River valley increases,while the WPD over north of the Yangtze River valley decreases.The WPD changes are dominated by an anomalous anticyclone located in the northwestern Pacific.The anticyclone leads to strong southerly winds in southern China and thereby enhances the WPD.In regions north of the Yangtze River valley,the low surface pressure gradient causes a reduction in wind speed and thereby a weak WPD.(3)The near-surface wind speed had decreased significantly over China during 1960-2013.The PDFs of small near-surface wind speed increased and large near-surface wind speed decreased.To examine the association with global warming,the dependence of the near-surface wind speed change over China on global mean temperature was analyzed by using interannual to decadal variations.Results show that the near-surface wind speed decreased by 1.166 m·s^-1over whole China for one degree warming in the global surface temperature.The large wind speed events exhibit larger changes per unit global warming than small and medium wind speed events.(4)Based on the observations,urbanization and the growth of vegetation contributed the decline of near-surface wind speed over eastern China.To examine the association with land use changes,the“observation minus reanalysis”method was used to evaluate the contrubitons.Results show that more than 50%decline of near-surface wind speed due to the land-use change over eastern China.The great influence was found in summer.(5)Compared with present day,mean annual wind energy will increase over northeast China,central China,southern China and coastal area and decrease over Tibet Plateau and Inner Mongolia under 1.5? and 2.0? warming targets.The large increases(decreases)are found in summer(winter)over central China,southern China and coastal area(over Inner Mongolia and Tibet Plateau).The 0.5 degree temperature warmer show little changes..Under 3.0? and 4.0? warming targets,wind power will only increased over southern China and decrease over other regions.Unerder 4.0? warming target,the wind energy will reduce by 4%over China as whole.The wind energy over China will decrease with the rising of global mean temperature.