The southeastern Tibetan Plateau(SETP)is a region in High Mountain Asia with the most serious glacier mass loss.However,long-term and large regional-scale studies that estimate glacier mass balance in this area remain...The southeastern Tibetan Plateau(SETP)is a region in High Mountain Asia with the most serious glacier mass loss.However,long-term and large regional-scale studies that estimate glacier mass balance in this area remain limited.In this study,we generated a KH-9 Digital Elevation Model(DEM)(covering 87.6%of the glacier area)for the 1970s from KH-9 Hexagon imagery and quantified geodetic glacier mass over the SETP from the 1970s to 2020 using KH-9 DEM,NASADEM and ICESat-2 ATL06 data.The results show that the SETP was in a state of serious mass loss(at a rate of−0.35±0.03 m w.e.per year)from the 1970s to 2020,and the rate of mass loss accelerated from−0.15±0.05 to−0.56±0.10 m w.e.per year between the 1970s–2000 and 2000–2020.Within the SETP,the glacier mass balance revealed a remarkable spatial heterogeneity.The maximum mean glacier mass loss rate was observed in the Hengduan Shan.Nyainqentanglha exhibited the highest acceleration in the mass loss rate since the 1970s.The warming of air temperature and decreasing snowfall can partly explain the accelerated glacier mass loss in the SETP.The study provides a new long-term glacier mass balance estimation covering almost the entire SETP that suggests the acceleration in glacier mass loss observed in the SETP since the 1970s is a regional tendency,which is crucial for understanding the relationship between glaciers and climate changes.展开更多
A good understanding of the quality of digital elevation model(DEM)is a perquisite for various applications.This study investigates the accuracy of three most recently released 1-arcsec global DEMs(GDEMs,Copernicus,NA...A good understanding of the quality of digital elevation model(DEM)is a perquisite for various applications.This study investigates the accuracy of three most recently released 1-arcsec global DEMs(GDEMs,Copernicus,NASA and AW3D30)in five selected terrains of China,using more than 240,000 high-quality ICESat-2(Ice,Cloud and land Elevation Satellite)ALT08 points.The results indicate the three GDEMs have similar overall vertical accuracy,with RMSE of 6.73(Copernicus),6.59(NASA)and 6.63 m(AW3D30).While the accuracy varies considerably over study areas and among GDEMs.The results show a clear correlation between the accuracy and terrain slopes,and some relationship between the accuracy and land covers.Our analysis reveals the land cover exerts a greater impact on the accuracy than that of the terrain slope for the study area.Visual inspections of terrain representation indicate Copernicus DEM exhibits the greatest detail of terrain,followed by AW3D30,and then by NASADEM.This study has demonstrated that ICESat-2 altimetry offers an important tool for DEM assessment.The findings provide a timely and comprehensive understanding of the quality of newly released GDEMs,which are informative for the selection of suitable DEMs,and for the improvement of GDEM in future studies.展开更多
基金This work was supported by the Program for National Natural Science Foundation of China(grant 41830105&42011530120)We acknowledged the German Aerospace Center(DLR)for providing the X-band SRTM DEM,NASA for the NASADEM,USGS for the KH-9 imagery,NSIDC for ICESat-2 ATL06 data,European Centre for Medium-Range Weather Forecasts(ECMWF)for ERA5 Land reanalysis data,and the Global Land Ice Measurements from Space initiative(GLIMS)for RGI 6.0 dataset。
文摘The southeastern Tibetan Plateau(SETP)is a region in High Mountain Asia with the most serious glacier mass loss.However,long-term and large regional-scale studies that estimate glacier mass balance in this area remain limited.In this study,we generated a KH-9 Digital Elevation Model(DEM)(covering 87.6%of the glacier area)for the 1970s from KH-9 Hexagon imagery and quantified geodetic glacier mass over the SETP from the 1970s to 2020 using KH-9 DEM,NASADEM and ICESat-2 ATL06 data.The results show that the SETP was in a state of serious mass loss(at a rate of−0.35±0.03 m w.e.per year)from the 1970s to 2020,and the rate of mass loss accelerated from−0.15±0.05 to−0.56±0.10 m w.e.per year between the 1970s–2000 and 2000–2020.Within the SETP,the glacier mass balance revealed a remarkable spatial heterogeneity.The maximum mean glacier mass loss rate was observed in the Hengduan Shan.Nyainqentanglha exhibited the highest acceleration in the mass loss rate since the 1970s.The warming of air temperature and decreasing snowfall can partly explain the accelerated glacier mass loss in the SETP.The study provides a new long-term glacier mass balance estimation covering almost the entire SETP that suggests the acceleration in glacier mass loss observed in the SETP since the 1970s is a regional tendency,which is crucial for understanding the relationship between glaciers and climate changes.
基金supported by the National Natural Science Foundation of China[grant number 41201429,42171375].
文摘A good understanding of the quality of digital elevation model(DEM)is a perquisite for various applications.This study investigates the accuracy of three most recently released 1-arcsec global DEMs(GDEMs,Copernicus,NASA and AW3D30)in five selected terrains of China,using more than 240,000 high-quality ICESat-2(Ice,Cloud and land Elevation Satellite)ALT08 points.The results indicate the three GDEMs have similar overall vertical accuracy,with RMSE of 6.73(Copernicus),6.59(NASA)and 6.63 m(AW3D30).While the accuracy varies considerably over study areas and among GDEMs.The results show a clear correlation between the accuracy and terrain slopes,and some relationship between the accuracy and land covers.Our analysis reveals the land cover exerts a greater impact on the accuracy than that of the terrain slope for the study area.Visual inspections of terrain representation indicate Copernicus DEM exhibits the greatest detail of terrain,followed by AW3D30,and then by NASADEM.This study has demonstrated that ICESat-2 altimetry offers an important tool for DEM assessment.The findings provide a timely and comprehensive understanding of the quality of newly released GDEMs,which are informative for the selection of suitable DEMs,and for the improvement of GDEM in future studies.
