Using TanDEM-X Pursuit Monostatic Observations with a Large Perpendicular Baseline to Extract Glacial Topography  
[PERSON]  
1 Department of Geological Sciences, Pusan National University, Pusan 46241, Korea; [EMAIL_ADDRESS]  
[PERSON]  
2 Department of Earth & Environment, Florida International University, FL 33199, USA; [EMAIL_ADDRESS]  
[PERSON]  
3 Department of Marine Geosciences, University of Miami, FL 33149, USA; [PERSON]DDRESS]  
[PERSON]  
4 Unit of Arctic Sea-Ice Prediction, Korea Polar Research Institute, Incheon 21990, Korea; [EMAIL_ADDRESS]  
[PERSON]  
5 Department of Earth System Sciences, Yonsei University, Seoul 03722, Korea; [PERSON]L_ADDRESS]  
[PERSON]  
6 Department of Energy & Mineral Resources Engineering, Sejong University, Seoul 05006, Korea  
Correspondence: [EMAIL_ADDRESS]; Tel. : +82-2-3408-37235513  
as well as for constraining regional and global climate change models. In glacier monitoring, precise topographic observations of glaciers have been an invaluable resource to evaluate glaciological mass balance affecting sea-level rise [10; 11; 12; 13; 14; 15]. [PERSON] el al. reported a rapid change of ice discharge in the Greenland outlet glacier using a satellite-derived surface elevation model [16]. High-resolution digital elevation models (DEMs) using an unmanned aerial vehicle (UAV) were successfully utilized to assess calving dynamics at the Greenland outlet glacier [17]. A review paper pointed out that the high-resolution DEMs can be very useful resources to describe ice sheet mass balance in Greenland [18]. A time-series of DEMs derived imaging sensors, including both optic and radar instruments, can be useful to estimate ice budget in glacier monitoring. A few studies showed that conventional TanDEM-X DEM is a valuable resource to calculate elevation change in glacier monitoring [19; 20]. Although high-resolution DEMs are an essential resource to understand mass balance in ice sheets, the generation of precise DEMS in the cryosphere remains a difficult task. The main obstacles in observing the surface height of the cryosphere might be inaccessibility due to inhospitable conditions and the darkness of the polar night. Developments in remote-sensing techniques have aided in the successful development of DEMs over glacial surfaces to overcome these obstacles. Topographic information of glaciers has been measured using space-based radar and laser altimetry, using satellites such as ERS-1/2, Envisat, ICESat, and CryoSat-2. Although satellite altimetry observations can retrieve the precise surface height of a glacier with a single observation, it is difficult to inspect the surface of glaciers in much detail because the observations provide limited measurements between orbits. Moreover, the observations often lose accuracy where the gradient of a slope significantly changes [21]. Despite the inhospitable conditions that restrict access to the cryosphere, airborne sensors such as those used during Operation IceBridge have been successfully used in previous campaigns. However, it is impossible to generate a precise DEM of the entire polar region because of costs and access restrictions. Near-global DEMs, such as the Shuttle Radar Topographic Mission (SRTM) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) have been released. While the GDEM utilizes stereo optical imagery, the SRTM data relies on single-pass InSAR observations. Both DEMs, particularly the SRTM DEM, are quite limited for use in cryospheric studies because the coverage of the SRTM DEM extends only from 56\({}^{\circ}\)S to 60\({}^{\circ}\)N, and that of the GDEM extends from 83\({}^{\circ}\)N to 83\({}^{\circ}\)S. The vertical accuracy of these DEMs ranges from \(\pm\)6 to \(\pm\)16 m [22], and outdated topographic information might prevent the accurate calculation of glacial characteristics. In addition, the spatial resolution of both DEMs is approximately 30 m, which is too coarse to investigate detailed features of a glacier.