Investigating the bias of TanDEM-X digital elevation models of glaciers on the Tibetan Plateau: impacting factors and potential effects on geodetic mass-balance measurements

• Published in: Journal of Glaciology
• Main Authors: Li, Jia, Li, Zhi-Wei, Hu, Jun, Wu, Li-Xin, Li, Xin, Guo, Lei, Liu, Zhuo, Miao, Ze-Lang, Wang, Wei, Chen, Jun-Li
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2021
• Subjects: Geodetic Glacier; Journal of Glaciology
• Online Access: http://dx.doi.org/10.1017/jog.2021.15; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143021000150

Abstract The TanDEM-X DEM is a valuable data source for estimating glacier mass balance. However, the accuracy of TanDEM-X elevation over glaciers can be affected by microwave penetration and phase decorrelation. To investigate the bias of TanDEM-X DEMs of glaciers on the Tibetan Plateau, these DEMs were subtracted from SPOT-6 DEMs obtained around the same time at two study sites. The average bias over the studied glacier areas in West Kunlun (175.0 km 2 ) was 2.106 ± 0.012 m in April 2014, and it was 1.523 ± 0.011 m in Geladandong (228.8 km 2 ) in October 2013. By combining backscatter coefficients and interferometric coherence maps, we found surface decorrelation and baseline decorrelation can cause obvious bias in addition to microwave penetration. If the optical/laser data and winter TanDEM-X data were used as new and historic elevation sources for mass-balance measurements over an arbitrary observation period of 10 years, the glacier mass loss rates in West Kunlun and Geladandong would be potentially underestimated by 0.218 ± 0.016 and 0.158 ± 0.011 m w.e. a −1 , respectively. The impact is therefore significant, and users should carefully treat the bias of TanDEM-X DEMs when retrieving a geodetic glacier mass balance.