HRES -- Synthetic high-resolution Antarctic bed elevation

Full description

HRES is a high-resolution (100m) synthetic bed elevation terrain for the whole Antarctic continent. The synthetic bed surface preserves topographic roughness characteristics of airborne and ground-based ice-penetrating radar data from the Bedmap1 compilation and the ICECAP consortium. Broad-scale features of the Antarctic landscape are incorporated from a lowpass filter of the Bedmap2 bed elevation data. The data are available in NetCDF classic format on a 100m resolution grid in a Polar Stereographic Projection (Central Meridian 0 degrees, Standard Parallel 71 degrees S) with respect to the WGS84 geoid. The 100m grid is 66661 rows by 66661 columns, where the corner of the lower left cell is located at a polar stereographic easting and northing of -3333000 m and -3333000 m, respectively. The value for missing data is -9999.

A minor update was made to the dataset on 2021-12-23 to correct an error in the data.

The issue was that while the x and y dimensions were defined in the netcdf file (i.e. how many points in each dimension) the corresponding variables defining the actual locations were not defined. Therefore, when the file was loaded, the software was defaulting to using the index count to be the coordinate location, which would look like 1m data spacing

To fix this, the coordinate variables have been defined, and also the order the data was written in to correspond to what viewing programs such as ferret expect has been swapped.

The actual post-processing on the original data (hres.nc) was

gdal_translate -of netCDF -co WRITE_BOTTOMUP=NO NETCDF:"hres.nc":bed_elevation hres_temp_1.nc

ncpdq -a -y,x hres_temp_1.nc hres_temp_2.nc
ncap2 -S hres_nco.txt hres_temp_2.nc hres_revised.nc

Where the file hres_nco.txt contains the following 8 lines
y=array(-3331000f,100,$y);
x=array(-3331000f,100,$x);
y@long_name="Northing";
y@Standard_name="Northing";
y@units="m";
x@long_name="Easting";
x@Standard_name="Easting";
x@units="m";

The second processing step (ncpdq) requires a system with a bit over 40GB of memory.

Lineage

Progress Code: completed

Statement: The user is referred to the manuscripts describing the original datasets used in the simulation of HRES -- namely, Fretwell et al. (2013) for Bedmap2 and references therein for the Bedmap1 flight line data, and Roberts et al. (2011) for ICECAP -- for a thorough description of error and uncertainty associated with the original data. The data that we used to simulate the terrain are from many different sources over different timeframes. Here is a summary of what the dates in temporal coverage refer to: - For the ICECAP flightlines, the data were collected between 2008 and 2012 - For the Bedmap1 tracks, the data were collected by multiple institutes over the period 1951-1999. - For the low-pass Bedmap2 part of our HRES terrain, the data included the same data that was in Bedmap1, plus other data, from 1951-2013.

Notes

Purpose
Although not intended as a substitute for Bedmap2, the simulated bed elevation terrain has applicability in high-resolution ice-sheet modelling studies, including investigations of the interaction between topography, ice-sheet dynamics and hydrology, where processes are highly sensitive to bed elevations.