Reconstruction And Spatiotemporal Variation Analysis Of Land Surface Albedo And Its Influencing Factors In Guizhou Province From 2001 To 2020

The solar energy reflected by the Earth back into space is known as planetary albedo.This reflected energy is a fundamental component of the Earth’s energy balance,and the processes that control the size,distribution,and variability of albedo shape the climate and climate change of the Earth.Therefore,studying the spatial and temporal variations of surface albedo on the Earth’s surface and its influencing factors based on long-term satellite remote sensing observations is of great significance.In this study,we conducted an in-depth exploration and analysis of the spatial and temporal patterns of surface albedo and its influencing factors in the karst mountainous area of Guizhou,China,based on the longterm time series of Moderate Resolution Imaging Spectroradiometer(MODIS)products.We reconstructed a long-term time series dataset of surface albedo in the karst mountainous area of Guizhou,evaluated the accuracy and spatiotemporal completeness of the reconstructed dataset,clarified the spatial and temporal patterns of surface albedo in the karst mountainous area of Guizhou from 2001 to 2020,and preliminarily explained the dominant driving factors and mechanisms of surface albedo variability in this region.The main research results and conclusions are as follows:(1)Six commonly used time series reconstruction methods of different types were employed to reconstruct the surface albedo in the karst mountainous area of Guizhou.The reconstruction performance and accuracy were verified,and a suitable method for reconstructing the time series of surface albedo in the karst mountainous area of Guizhou was determined.The reconstructed time series showed high consistency with the verification time series: with 50% missing data in the time series,the correlation coefficient(R)between the reconstructed and verification time series was 0.88,the root-mean-square error(RMSE)was 0.0097,and the mean absolute error(MAE)was 0.0065.This method was used to generate the MODIS shortwave surface albedo dataset for the karst mountainous area of Guizhou.The analysis results showed that the reconstructed time series had the advantages of temporal continuity and spatial integrity,and was suitable for the analysis of spatial and temporal variations of surface albedo in the karst mountainous area of Guizhou.(2)Based on the MODIS surface albedo dataset,the spatial and temporal trends of surface albedo in the karst mountainous area of Guizhou over the past 20 years(2001-2020)were obtained.The areas with increasing surface albedo were mainly distributed in Weining County in the far west of Bijie City,Chishui City in the northwest of Zunyi City,and most of the central Guizhou region,while other areas showed a decreasing trend in surface albedo.The surface albedo in the summer showed an increasing trend,while in the winter it showed a decreasing trend,and overall,it showed a decreasing trend and will continue to decrease in the near future.It was also found in the study that the surface albedo anomalies in Guizhou exhibited irregular and frequent oscillations.(3)Based on MODIS products and related influential factor data,the spatio-temporal distribution maps of driving factors and mechanisms for dynamic changes in surface albedo in Guizhou were obtained.It was found that the dominant factors causing spatial differentiation in surface albedo in the karst mountainous area of Guizhou are vegetation leaf area index,land use type,and rock composition type.The dominant driving factors for the spatio-temporal changes in surface albedo in the karst mountainous area of Guizhou are soil moisture,vegetation leaf area index,and land use type changes.The spatio-temporal changes in surface albedo in Guizhou are affected by both natural changes and human activities,with human activities driving an increase in surface albedo and natural changes driving a decrease in surface albedo.Overall,the surface albedo in Guizhou is mainly driven to decrease by natural changes and will continue this trend in the future.(4)This study analyzed the spatio-temporal trends of surface albedo in the mountainous areas of Guizhou,updated the understanding of the spatio-temporal patterns of surface albedo in recent decades,explored the dominant driving factors and mechanisms for spatio-temporal changes in surface albedo in Guizhou,and laid the foundation for further exploration and analysis of the response and feedback mechanisms of surface albedo to climate change and human activities.