High-resolution topography of the Antarctic Peninsula combining the TanDEM-X DEM and Reference Elevation Model of Antarctica (REMA) mosaic

Abstract

Abstract. The Antarctic Peninsula (AP) is one of the widely studied polar regions because of its sensitivity to climate change and potential contribution of its glaciers to global sea level rise. Precise digital elevation models (DEMs) at a high spatial resolution are much demanded for investigating the complex glacier system of the AP at fine scales. However, the two most recent circum-Antarctic DEMs, the 12 m TanDEM-X DEM (TDM DEM) from bistatic interferometric synthetic aperture radar (InSAR) data acquired between 2013 and 2014 and the Reference Elevation Model of Antarctica mosaic (REMA mosaic) at an 8 m spatial resolution derived from optical data acquired between 2011 and 2017 have specific individual limitations in this area. The TDM DEM has the advantage of good data consistency and few data voids (approx. 0.85 %), but there exist residual systematic elevation errors such as phase-unwrapping errors in the non-edited DEM version. The REMA mosaic has high absolute vertical accuracy, but on the AP it suffers from extended areas with data voids (approx. 8 %). To generate a consistent, gapless and high-resolution topography product of the AP, we fill the data voids in the TDM DEM with newly processed TDM raw DEM data acquired in austral winters of 2013 and 2014 and detect and correct the residual systematic elevation errors (i.e., elevation biases) in the TDM DEM with the support of the accurately calibrated REMA mosaic. Instead of a pixelwise replacement with REMA mosaic elevations, these provide reference values to correct the TDM elevation biases over entire regions detected through a path propagation algorithm. The procedure is applied iteratively to gradually correct the errors in the TDM DEM from a large to small scale. The proposed method maintains the characteristics of an InSAR-generated DEM and is minimally influenced by temporal or penetration differences between the TDM DEM and REMA mosaic. The performance of the correction is evaluated with laser altimetry data from Operation IceBridge and ICESat-2 missions. The overall root mean square error (RMSE) of the corrected TDM DEM has been reduced from more than 30 m to about 10 m which together with the improved absolute elevation accuracy indicates comparable values to the REMA mosaic. The generated high-resolution DEM depicts the up-to-date topography of the AP in detail and can be widely used for interferometric applications as well as for glaciological studies on individual glaciers or at regional scales.

TanDEM-X PolarDEM 90 m of Antarctica: generation and error characterization

“…A further refinement of this data set might be possible by correcting the penetration bias, as shown, for example, by Abdullahi et al (2019) on the basis of coherence and amplitude or by Rott et al (2021) on the basis of the interferometric volume correlation coefficient, which would improve the comparability with other data. An adequate handling of individual height offset scenes like in Dong et al (2021) and a re-calibration near the Antarctic Peninsula down to Getz glacier could lead to a further improvement of this data set. Also, the amplitude mosaic itself could be further exploited in a more detailed analysis and in comparison with other backscatter data, e.g., RADARSAT or ERS-1/2 at C-band or PALSAR-2 at L-band.…”

“…18). These so-called PI-jump errors (Rizzoli et al, 2017;Dong et al, 2021) could not be detected fully like for almost the rest of the globe due to the lack of adequate reference data. On the other hand, especially in East Antarctica, some rectangular offset area divergences are visible, e.g., blue quadratic areas near the pole, which might suggest a processing error in REMA as TanDEM-X was processed in geographic coordinates.…”

Where the White Continent Is Blue: Deep Learning Locates Bare Ice in Antarctica

“…We complemented the seven‐band composite of MODIS data with three additional data sets (Text S6 in Supporting Information ): (a) The cloud‐free, MODIS‐based mosaic of surface morphology (MOA2009) (Haran et al., 2021; Scambos et al., 2007) to provide additional data in areas where our MODIS composite is, for example, distorted by clouds that were not correctly masked out; (b) The RADARSAT‐2 Antarctica mosaic (Crevier et al., 2010; MacDonald, Dettwiler and Associates (MDA), 2014), a C‐band radar signal that shows low backscatter values co‐located with blue ice. As C‐band radar can penetrate several meters into snow (Jezek, 1999; Wessel et al., 2021), these data allow, on the one hand, to detect blue ice in areas where snow patches hamper the observation of blue ice that directly underlies these typically thin layers of snow (of up to 50 cm; Sinisalo & Moore, 2010) in multi spectral data; on the other hand, C‐band radar data is difficult to use or interpret without complementary data; (c) Surface elevation data (TanDEM‐X PolarDEM) (Dong et al., 2021; German Aerospace Center (DLR), 2020; Wessel et al., 2021), as the occurrence of blue ice is strongly linked to the surface topography (Takahashi et al., 1992). For example, BIAs are often located close to mountains protruding the ice (nunataks), which can act as barriers to the ice flow upstream, redirecting the ice flow toward the surface (Sinisalo & Moore, 2010).…”

Mass changes of the northern Antarctic Peninsula Ice Sheet derived from repeat bi-static SAR acquisitions for the period 2013–2017

“…A reference DEM (refDEM) is needed for the generation of SAR DEMs based on differential interferometry. The recently published high-resolution DEM of the AP (Dong et al, 2021) based on the global TanDEM-X DEM at 12 m spatial resolution is employed. The authors used information from the Reference Elevation Model of Antarctica (REMA) (Howat et al, 2019) to correct residual systematic elevation errors in the global TanDEM-X DEM, and to obtain enhanced surface height data for the AP.…”