Spatio-Temporal Variation Characteristics Of Surface Albedo And Analysis Of Influential Factors In Junggar Basin

Surface albedo influences the balance between surface radiation and energy,thereby affecting regional and global climates.The typical desert environment in Junggar Basin,located in the hinterland of Central Asia,is an indicator of climate change in arid areas.In the process of climate change,the unique underlying surface can sensitively reflect the dry and wet,cold and warm processes of regional climate change.Hence,the temporal and spatial variation characteristics of surface albedo in Junggar Basin,as well as its influencing factors,are studied,which has irreplaceable regional characteristics and scientific significance for correctly understanding the land surface characteristics of Junggar Basin,and improving the ecological environment and climate monitoring.It also provides theoretical foundation for objective evaluation of the land surface change and its positive and negative feedback response mechanism in arid areas under global climate change.Taking Junggar Basin as the research object,the surface albedos in short wave,near infrared and surface albedo of visible light are retrieved based on MODIS satellite remote sensing data and MOD09A1 product.The temporal and spatial variation characteristics of surface albedo,air temperature,precipitation and NDVI in Junggar Basin from 2001 to 2018,and the variation characteristics of surface albedo of different land use types are analyzed based on meteorological data,vegetation NDVI and land use type data.After that,the correlation among surface albedo of different bands and air temperature,precipitation and NDVI is analyzed,and the temporal and spatial response of surface albedo and influencing factors is also discussed.The main conclusions of this paper are as follows:(1)There are prominent spatial and regional differences on the surface albedo of short wave,near infrared and visible light in Junggar Basin,which shows the distribution law of high in northeast and low in southwest,and the average surface albedo for many years meets the requirement of near infrared > short wave > visible light.About the spatial distribution of interannual variation rate of surface albedo in 3different bands in Junggar Basin,it shows the change trend of "increasing in southwest and northeast margins,and decreasing in north and southeast margins".The standard deviation of surface albedo in different bands is mainly distributed in the range of 0.015-0.030,which meets the requirement of visible light > short wave > near infrared.The standard deviation of surface albedo reaches the highest in winter and the lowest in summer.The change of surface albedo is closely related to the seasonal change of surface cover type.(2)The surface albedo of different land use types has obvious difference characteristics in different wave bands in Junggar Basin.The surface albedo of other first-class and second-class land types all meet the characteristics of near infrared > short wave > visible light,except for lakes and reservoirs.The interannual change trend of surface albedo of different land use types in the three bands from 2010 to 2018 is slightly significantly higher than that in 2000 to 2010,and all the first-class land use types in the short wave band passed the significance test of 0.05 from 2010 to 2018.The interannual variation rate of surface albedo of land use types in Junggar basin showed a weak growth trend over the past 18 years,and the interannual variation rate was slight and stable in the whole.The results will lay a foundation for the study of surface spectral radiation and energy balance of the studied area.(3)The surface albedo in short wave,near infrared and visible light bands in Junggar Basin from 2001 to 2018 is negatively correlated with air temperature.The correlation coefficients are-0.44,-0.42 and-0.45 respectively.There is a weak positive correlation with precipitation,and the correlation coefficients are0.25,0.19 and 0.27 respectively.There is a negative correlation with NDVI,and the correlation coefficients are-0.35,-0.32 and-0.39 respectively.The correlation coefficient values of air temperature,precipitation,NDVI and surface albedo in different bands meet the following requirement: visible light > short wave >near infrared.Among them,the absolute value of correlation coefficient value between air temperature and surface albedo is the highest,which is the most significant factor affecting the change of surface albedo,followed by NDVI.That of the precipitation ranks the last place.In general,air temperature is the dominant factor influencing the change of surface albedo in Junggar Basin.