Impacts Of Wind Farms On Land Surface Temperature And Vegetation In Hebei Bashang Based On Satellite Remote Sensing Data

The extensive use of wind energy resources in China not only brings huge economic benefits but also reduces environmental pollution caused by various fossil fuels.With the increasing scale of wind farm construction,its climate and ecological effects have attracted people's attention.Some studies have shown that the rotation of the rotor blades will increase surface roughness and then enhance turbulence in the rotor wakes by changing the stability of the atmospheric boundary layer(ABL).If these changes are spatially large enough,they may affect the local and even regional weather and climate.With increasing installed capacity of wind farms,a correct understanding of the possible impacts of wind power on climate are needed.It is of great significance for the scientific use of wind energy resources and ensuring the sustainable development of energy in China.Based on MODIS(Moderate-Resolution Imaging Spectroradiometer)satellite data from 2003 to 2019,this paper explores the impact of wind farms in Bashang Region in the Northwest of Hebei Province on land surface temperature(LST),normalized difference vegetation index(NDVI),enhanced vegetation index(EVI),leaf area index(LAI),and gross primary productivity(GPP).Combined on surface albedo and land use data.The important finds and main conclusions are drawn as follows:(1)From 2003 to 2019,the influence of wind farm operation on LST(Land Surface Temperature)in the study area is complex,and there is a phenomenon of temperature increase inside the wind farm.The western hilly area(Shangyi and Zhangbei wind farms)shows that,compared with the surrounding areas not affected by wind farms,the surface temperature within wind farms increased significantly in spring and summer,especially during spring night with an increasing trend of 0.379?/10 a,followed by summer night with increasing trends of 0.206?/10 a,and the warming effect has a stronger spatial coupling with WFM pixels.The northern hilly area(Kangbao and Inner Mongolia wind farms)shows that the surface temperature within wind farms increased significantly in spring night(0.228?/10 a).The local large turbulence is obvious in eastern mountain area(Guyuan and Chongli wind farms),so the warming trend is not significant.Compared with other studies,the temperature increase caused by wind farms in this study area is weaker.(2)Although wind farms in Bashang have impacts on LST,compared with other studies the increasing trends caused by wind farms in this study area are weak and much smaller than the interannual LST increasing trend in the Bashang area(0.817°C/10 a),the land surface temperature increases caused by the operation of wind turbines is negligible compared with which caused by fossil fuels.(3)Affected by wind farms in the western hilly area,the NDVI,EVI,LAI,and GPP in summer all show a significant downward trend,-0.018/10 a,-0.011/10 a,-0.051/10 a and-6.677 g C/m~2/10 a,the spring GPP shows an increasing trend,1.133 g C/m~2/10 a.The grassland in spring is greatly affected by the wind farm,and other land types are not.The wind farm in the northern hilly area is conducive to the growth of vegetation in spring.The growth trend of LAI reaches 0.007/10 a,and the GPP is 2.06 g C/m~2/10 a,the NDVI is 0.002/10 a.The EVI in summer shows a downward trend,which is-0.009/10 a,and the LAI also decreases significantly,which is-0.038/10 a.In the eastern mountain area,the vegetation is also less affected by the wind farm due to the insignificant increase in LST temperature.The impact of wind farms on vegetation is far less than the impact of urban expansion,reclamation,and uncontrolled grazing.(4)The impact mechanism of wind farms in the study area on the LST and vegetation is: as the ABL is stable at night,the turbulence enhanced vertical mixing in the wakes generated by windturbine rotors.The warmer air overlaying cooler air is brought near the ground,and the land surface is warmed up.Increasing LST at night in spring brings melting water of ice and snow,and the soil water content increases.The thermal insulation effect on the surface can prevent freezing damage,which is conducive to the growth of vegetation in spring;summer is hot and dry,and the phenomenon of nighttime temperature increase leads to a decrease in soil water content,which is not conducive to summer vegetation grow.