polartoolkit.fetch.bedmachine

bedmachine(layer, reference='eigen-6c4', region=None, spacing=None, registration=None, hemisphere=None, epsg=None, **kwargs)

Load BedMachine topography data from either Greenland (v5) or Antarctica (v3), from Morlighem[1] or IceBridge BedMachine Greenland, Version 5[2].

Antarctica: Accessed from NSIDC via https://nsidc.org/data/nsidc-0756/versions/3. Also available from ldeo-glaciology/pangeo-bedmachine

Greenland: Accessed from NSIDC via https://nsidc.org/data/idbmg4/versions/5

Referenced to the EIGEN-6C4 geoid. To convert to be ellipsoid-referenced, we add the geoid grid. use reference=’ellipsoid’ to include this conversion in the fetch call.

For Antarctica: Surface and ice thickness are in ice equivalents. Actual snow surface is from REMA [3], and has had firn thickness added(?) to it to get Bedmachine Surface.

To get snow surface: surface+firn To get firn and ice thickness: thickness+firn

Here, icebase will return a grid of surface-thickness This should be the same as snow-surface - (firn and ice thickness)

Requires an EarthData login, see Tutorials/Download Polar datasets for how to configure this.

Parameters:

• layer (str) – choose which layer to fetch: ‘bed’, ‘dataid’, ‘errbed’, ‘firn’, ‘geoid’, ‘mask’, ‘source’, ‘surface’, ‘ice_thickness’; ‘icebase’ will give results of surface-thickness

• reference (str) – choose whether heights are referenced to ‘eigen-6c4’ geoid or the ‘ellipsoid’ (WGS84), by default is eigen-6c4’

• region (tuple[float, float, float, float], optional) – region to clip the loaded grid to, in format [xmin, xmax, ymin, ymax], by default doesn’t clip

• spacing (str or int, optional) – grid spacing to resample the loaded grid to, by default 500m. If spacing >= 5000m, will resample the grid to 5km, and save it as a preprocessed grid, so future fetch calls are performed faster.

• registration (str, optional) – change registration with either ‘p’ for pixel or ‘g’ for gridline registration, by default is None.

• hemisphere (str, optional) – choose which hemisphere to retrieve data for, “north” or “south”, by default None

• epsg (str | None) – choose which region to retrieve data for, either “3031” or “3413”, by default None

• **kwargs (Any) – additional keyword arguments to pass to the resample_grid function

Returns:

Returns a loaded, and optional clip/resampled grid of Bedmachine.

Return type:

xarray.DataArray

References

[1]

M. Morlighem. MEaSUREs BedMachine Antarctica, Version 3. 2022.

[2]

IceBridge BedMachine Greenland, Version 5. https://nsidc.org/data/idbmg4/versions/5, October 2020.

[3]

Ian M. Howat, Claire Porter, Benjamin E. Smith, Myoung-Jong Noh, and Paul Morin. The Reference Elevation Model of Antarctica. The Cryosphere, 13(2):665–674, February 2019. doi:10.5194/tc-13-665-2019.