Abstract
Abstract. We present Bedmap2, a new suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of the Antarctic south of 60° S. We derived these products using data from a variety of sources, including many substantial surveys completed since the original Bedmap compilation (Bedmap1) in 2001. In particular, the Bedmap2 ice thickness grid is made from 25 million measurements, over two orders of magnitude more than were used in Bedmap1. In most parts of Antarctica the subglacial landscape is visible in much greater detail than was previously available and the improved data-coverage has in many areas revealed the full scale of mountain ranges, valleys, basins and troughs, only fragments of which were previously indicated in local surveys. The derived statistics for Bedmap2 show that the volume of ice contained in the Antarctic ice sheet (27 million km3) and its potential contribution to sea-level rise (58 m) are similar to those of Bedmap1, but the mean thickness of the ice sheet is 4.6% greater, the mean depth of the bed beneath the grounded ice sheet is 72 m lower and the area of ice sheet grounded on bed below sea level is increased by 10%. The Bedmap2 compilation highlights several areas beneath the ice sheet where the bed elevation is substantially lower than the deepest bed indicated by Bedmap1. These products, along with grids of data coverage and uncertainty, provide new opportunities for detailed modelling of the past and future evolution of the Antarctic ice sheets.
Highlights
The major improvement in coverage and precision that could be achieved by incorporating these data into a single new compilation is obvious. We present such a compilation, Bedmap2, which maintains several useful features of Bedmap1, but provides many improvements; higher resolution, orders of magnitude increase in data volume, improved data coverage and precision; improved GIS techniques employed in the gridding; better quality assurance of input data; a more thorough mapping of uncertainties; and fewer inconsistencies in the gridded products. It is more than a decade since grids of ice-surface elevation, ice thickness and subglacial topography for Antarctica were presented by the BEDMAP Consortium as digital products, and as a printed map (Lythe et al, 2000)
This model relies on the assumption that in mountainous areas where ice fills the valleys, there is a general correlation between ice thickness and the distance from rock outcrops
The following modifications were made to the original thin ice model: (1) The vector data used to describe the rock outcrops was taken from an updated digital dataset
Summary
It is more than a decade since grids of ice-surface elevation, ice thickness and subglacial topography for Antarctica were presented by the BEDMAP Consortium as digital products (hereafter we refer to these products collectively as Bedmap, Lythe et al, 2001), and as a printed map (Lythe et al, 2000). Bedmap products have been widely used in a variety of scientific applications, ranging from geological (e.g., Jamieson et al, 2005) and glaciological modelling (e.g., Wu and Jezek, 2004), to support for geophysical data interpretation (e.g., Riedel et al, 2012), as a basis for tectonic interpretation (e.g., Eagles et al, 2009), as a baseline for comparison of newly-acquired subglacial in-. The general approach used to derive the Bedmap products was to incorporate all available data, both geophysical and cartographic, and in particular, we endeavoured to include all measurements available to date. We describe the steps of these processes in detail. Some steps required specific judgments to be made with regard to conflicting measurements, with the consequence that not all measurements are honoured.
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