Digital Elevation Models(DEMs)for Antarctica are critical datasets for general circulation models,change analysis of ice sheet dynamics and logistical planning of field expeditions.To date,there are five different DEM...Digital Elevation Models(DEMs)for Antarctica are critical datasets for general circulation models,change analysis of ice sheet dynamics and logistical planning of field expeditions.To date,there are five different DEMs covering all of Antarctica,all of which were derived from satellite radar or laser altimetry data in combination with ground data.Since the margins of ice sheets are highly dynamic in space and time,DEMs of Antarctica should be updated frequently as new data become available.We used Radar Altimeter(RA-2)data from Envisat and laser altimeter(GLAS)data from ICESat to create an up-to-date DEM of Antarctica with high accuracy and precision of elevation measurement.In this paper,these two different sources of satellite altimeter data from 2003 to 2009 were integrated to generate a DEM for the entire continent of Antarctica.We applied five different quality judgment rules to filter unreliable ICESat/GLAS data;as a result,8.36%of the data were filtered out.A relative correction method based on speckle geometry intersection was used to correct Envisat RA-2 elevations to ICESat/GLAS.The data were interpolated to a regu-lar 1000 m polar stereographic grid using ordinary Kriging after semi-variance analysis.The accuracy of the final DEM was assessed through a comparison with two airborne LiDAR datasets,a field GPS strip from China's Zhongshan Station to Dome A and the most recently published DEM.The comparison result shows that the error of the new DEM is from 32.1 m to 27.84 m,and the distribution of errors depends on the surface slope.The new DEM shows an obvious improvement on steep slopes,including the quickly changing ice sheet margin areas.展开更多
文摘Digital Elevation Models(DEMs)for Antarctica are critical datasets for general circulation models,change analysis of ice sheet dynamics and logistical planning of field expeditions.To date,there are five different DEMs covering all of Antarctica,all of which were derived from satellite radar or laser altimetry data in combination with ground data.Since the margins of ice sheets are highly dynamic in space and time,DEMs of Antarctica should be updated frequently as new data become available.We used Radar Altimeter(RA-2)data from Envisat and laser altimeter(GLAS)data from ICESat to create an up-to-date DEM of Antarctica with high accuracy and precision of elevation measurement.In this paper,these two different sources of satellite altimeter data from 2003 to 2009 were integrated to generate a DEM for the entire continent of Antarctica.We applied five different quality judgment rules to filter unreliable ICESat/GLAS data;as a result,8.36%of the data were filtered out.A relative correction method based on speckle geometry intersection was used to correct Envisat RA-2 elevations to ICESat/GLAS.The data were interpolated to a regu-lar 1000 m polar stereographic grid using ordinary Kriging after semi-variance analysis.The accuracy of the final DEM was assessed through a comparison with two airborne LiDAR datasets,a field GPS strip from China's Zhongshan Station to Dome A and the most recently published DEM.The comparison result shows that the error of the new DEM is from 32.1 m to 27.84 m,and the distribution of errors depends on the surface slope.The new DEM shows an obvious improvement on steep slopes,including the quickly changing ice sheet margin areas.
