Study On Radiative Forcing Of Land Cover Change In Qinhuai Area

Land cover changes affect the surface radiation budget and energy balance by changing the surface albedo,generating radiative forcing,which has an impact on regional and global climate.In this paper,MODIS data were used to analyze the temporal and spatial variation characteristics of surface albedo change caused by land cover change in Huaihe area of the Qinling Mountains from 2001 to 2016.At the same time,CERES data were used to analyze the temporal and spatial variation characteristics of surface short-wave radiation,and the change of surface albedo in Qinling Huaihe area was calculated.Interannual scale radiative forcing reveals the impact of land cover change on climate change at the ecological zone scale.The main conclusions are as follows:(1)During 2001-2016,there were some changes in the types of land cover in the study area,of which the changed land use cover area accounted for 15.88%,and the most changed type was the transfer of grassland to forest land.The surface albedo in the qinling mountains and huaihe river area has obvious annual and inter-annual changes,and its spatial variation characteristics are closely related to the area changes of land cover types,and the characteristics of different land cover types are also different.The inter-annual variation of albedo in the study area is mainly due to decline,and there are differences between seasons,and the trend of winter is the strongest.Among the changes in the albedo of different types of surface cover,the change area is:grassland>woodland>cultivated land>water area>city and construction area>other,and the range of change is still mainly reduced.(2)Temporal and spatial variation characteristics of short-wave radiation on the surface of the study area in 2001-2016.The mean annual variation is 1.08 W m'2,and the spatial variation distribution decreases from west to east.During the year,the average radiant flux of short-wave radiation in the spring was 164.59 W·m-2,which showed a trend of increasing and decreasing from west to east.The average radiant flux in summer was 187.30 W·m-2,which increased significantly in the large area of the study area.The average radiant flux in autumn is 120.85 W m-2,and the change shows the interval of "rise-fall-rise-fall";the average radiant flux in winter is 91.24 Wm-2,and the trend of change is westward and eastward.(3)In the past 16 years,the radiation forcing caused by the change of albedo caused by different land cover changes has different magnitudes,different strengths and different occurrence ranges,which has brought certain impacts on climate change.In the radiative forcing caused by the change of albedo in the six types of land cover types,the negative forcing generated by cultivated land,woodland,grassland,and urban and construction areas is more than positive forcing,which brings cooling effect;the positive forcing produced by waters is more than negative.Forced,bringing a warming effect.Other types of changes are minimal and produce radiative forcing that is minimal.