A new 1 km digital elevation model of the Antarctic derived from combined satellite radar and laser data – Part 1: Data and methods

Abstract

Abstract. Digital elevation models (DEMs) of the whole of Antarctica have been derived, previously, from satellite radar altimetry (SRA) and limited terrestrial data. Near the ice sheet margins and in other areas of steep relief the SRA data tend to have relatively poor coverage and accuracy. To remedy this and to extend the coverage beyond the latitudinal limit of the SRA missions (81.5 • S) we have combined laser altimeter measurements from the Geosciences Laser Altimeter System onboard ICESat with SRA data from the geodetic phase of the ERS-1 satellite mission. The former provide decimetre vertical accuracy but with poor spatial coverage. The latter have excellent spatial coverage but a poorer vertical accuracy. By combining the radar and laser data using an optimal approach we have maximised the vertical accuracy and spatial resolution of the DEM and minimised the number of grid cells with an interpolated elevation estimate. We assessed the optimum resolution for producing a DEM based on a trade-off between resolution and interpolated cells, which was found to be 1 km. This resulted in just under 32% of grid cells having an interpolated value. The accuracy of the final DEM was assessed using a suite of independent airborne altimeter data and used to produce an error map. The RMS error in the new DEM was found to be roughly half that of the best previous 5 km resolution, SRA-derived DEM, with marked improvements in the steeper marginal and mountainous areas and between 81.5 and 86 • S. The DEM contains a wealth of information related to ice flow. This is particularly apparent for the two largest ice shelves -the Filchner-Ronne and Ross -where the surface expression of flow of ice streams and outlet glaciers canCorrespondence to: J. L. Bamber (j.bamber@bristol.ac.uk) be traced from the grounding line to the calving front. The surface expression of subglacial lakes and other basal features are also illustrated. We also use the DEM to derive new estimates of balance velocities and ice divide locations.

Temperature and Wind Climate of the Antarctic Peninsula as Simulated by a High-Resolution Regional Atmospheric Climate Model

“…We assume hydrostatic balance to hold at 5.5-km horizontal resolution: the validity of this assumption is confirmed by the fact that RACMO2.3 output agrees very well with surface and upper-air observations (see section 3), although obviously there would be processes that will be better resolved in a nonhydrostatic model [e.g., winds over sloping surfaces (Cassano and Parish 2000)]. The surface topography is based on the 100-m digital elevation model (DEM) from Cook et al (2012) for the grounded ice sheet north of 708S and on the 1-km DEM from Bamber and Gomez-Dans (2009) for the ice shelves and the remainder of the domain. This is a major update of the previous model topography, which was based on the Radarsat Antarctic Mapping Project, version 2, DEM (RAMPv2 DEM; Liu et al 2001).…”

“…Locations of SCAR-READER surface stations are marked (red diamonds), as is the location of AWS 14 (black circle). Model topography is based on digital elevation models from Cook et al (2012) and Bamber and Gomez-Dans (2009). White areas represent the floating ice shelves; colors represent the elevation of the grounded ice sheet.…”

An improved Antarctic dataset for high resolution numerical ice sheet models (ALBMAP v1)

“…3a for BEDMAP ice thickness). Since then, however, a new surface DEM has become available, incorporating IceSat laser altimetry data, as well as radar altimetry (Bamber et al, 2009;Griggs and Bamber, 2009a). In order to calculate the ice shelf thickness from the surface elevation, the respective densities of ocean water and ice need to be specified and an estimate of the depth and density of the firn layer is also required.…”

Glacial retreat in the Amundsen Sea sector, West Antarctica – first cosmogenic evidence from central Pine Island Bay and the Kohler Range

“…The WAIS is separated into well-defined drainage sectors following the satellite-borne remote sensing data from Bamber et al (2009a). Of interest for this study is the 'Amundsen sector' which is defined by four ice divides and covers a combined area of 417,000 km 2 ; references therein; Fig.…”