Present Day Antarctica

From Interactive System for Ice sheet Simulation
Jump to: navigation, search

Contents

Grid Details

These are 5km resolution, NetCDF files of Antarctica gathered from various data sources and interpolated, when necessary, onto the same grid using polar stereographic projection. Data download is available below as well as a change log which describes updates included in the current version of the data.

A table of the Data Sources.


Antartica: Ice surface velocity draped over ice surface elevation.


Mapping for Antarctica: Polar Stereographic(WGS84)
Standard Parallel    71.0
Latitude of Projection Origin   -90.0
False Easting    0.0
False Northing    0.0
Straight Vertical Longitude from Pole    0.0
Lower Left Corner X-Value   -2800 km
Lower Left Corner Y-Value   -2800 km

The Improved BEDMAP Data

The Antarctica data set contains the BEDMAP1_plus data field for topography. The areas of improved data are highlighted in the figure below. This data is courtesy of Hamish Pritchard and BAS. The new grid is a result of merging BEDMAP1, an AGASEA-BBAS-based grid from Texas University, and bathymetry grids by Nitsche(LDEO) and Tara Dean(BAS).

The new BEDMAP1_plus data for topography.

Antarctica Data Set Visuals

Antartica: The Topography, Surface Elevation and Ice Thickness fields from the data set for Antarctica.

Antartica: .

Antartica: .

Data Download

The recent changes data sets can be found in this change log.

Antarctica with Ice Shelves The data file contains the following fields in NetCDF format:
  • Latitude,
  • Longitude,
  • Mean Annual Surface Temperature (Comiso et al 2000 ),
  • Ice Thickness; Ice Thickness of Grounded Ice is calculated from surface elevation and topography. Ice shelf thickness was provided by J.A. Griggs and J.L. Bamber, July 2009, who warn that "This is a beta data product and should not be treated as a final product." The ice shelf thickness data should be referenced as "A new ice thickness dataset for the Antarctic ice shelves derived from satellite altimetry, J.A. Griggs and J.L. Bamber, in preparation for Journal of Glaciology, 2009",
  • Accumulation (Vaughan et al. 1999),
  • Ice Surface Elevation; Provided by J.A. Griggs and J.L. Bamber, July 2009. Data is regridded from a 1km Digital Elevation Model (DEM) and should be referenced to Bamber, J.L., J.L. Gomez-Dans and J.A. Griggs, The Cryosphere, 3, 101-111 (2009) and Griggs, J.A. and J.L. Bamber, The Cryosphere, 3, 113-123 (2009),
  • Bed Topography from BEDMAP1_plus (courtesy of Hamish Pritchard from BAS, bathymetry from Nitsche et al. 2007),
  • Basal Heat Flux (Shapiro and Ritzwoller 2004),
  • Basal Heat Flux (Fox Maule et al 2005) Please note that for the purposes of SeaRISE, GTHF should be capped at a value of 0.07 w/m^2, and the fields provided in the netCDF file are not capped at this value,
  • Thickness Mask (Thanks to Gael Durand and Catherine Ritz) from Bohlander and Scambos 2007,
  • Surface Velocity (x-component, y-component, and magnitude),
  • Melt (Ross ice streams),
  • Surface Balance Velocity.
Media:Antarctica_5km_withshelves_v0.75.nc
Antarctica without Ice Shelves This file was created for models that don't handle ice shelves very well. The data file contains the same fields as the "Antarctica with Ice Shelves" file described above but the data is different for three of the fields:
  • Ice Thickness
  • Ice Surface Elevation
  • Bed Topography

The differences are due to the removal of the ice shelves from the data.

Media:Antarctica_5km_woshelves_v0.75.nc
ANTARCTICA DEVELOPMENTAL DATA SET

Antarctica_5km_dev1.0.nc

An Antarctica "Developmental" Data Set has been created incorporating data described in

Le Brocq, Anne M; Payne, Antony J; Vieli, Andreas (2010): An improved Antarctic dataset for high resolution numerical ice sheet models (ALBMAP v1). Earth System Science Data, 2, 247-260. doi: 10.5194/essd-2-247-2010

This data set was downloaded from http://doi.pangaea.de/10.1594/PANGAEA.734145

Fields in the developmental data set taken directly from Le Brocq et al's data set are:

  • acca - accumulation - Athern et al
  • accr - accumulation - Van de Berg et al
  • bheatflx_fox - geothermal heat flux - Fox Maule et al
  • bheatflx_shapiro - geothermal heat flux - Shapiro & Ritzwoller
  • firn - firn correction
  • mask - grounded/floating ice mask
  • temp - surface air temperature
  • topg - bedrock topography
  • usrf - upper ice surface elevation

Fields in the developmental data set derived from Le Brocq et al's data set are:

  • usrf_noshelf - upper ice surface elevation with elevation set to zero beyond the grounding line specified by the mask
  • thk - ice thickness (calculated by subtracting the lower ice surface elevation from the upper ice surface elevation)
  • thk_noshelf - ice thickness with thickness set to zero beyond the grounding line specified by the mask

Fields retained from the SeaRISE standard data set described above are:

  • balvelmag - Balance Velocity Magnitude
  • lat - latitude
  • lon - longitude
  • melt - Basal Melting Rate
  • sealevel_time_series - Sea Level (variation from present)
  • surfvelx, surfvely, surfvelmag - Surface velocity components and magnitude
  • temp_time_series - Temperature (variation from present)

Notes: Le Brocq et al use a 1160x1120 grid whose grid points correspond with those in the standard 1200x1200 SeaRISE data set grid starting in the lower left hand corner. The temperature, geothermal heat flux (Shapiro & Ritzwoller), and bedrock topography fields from Le Brocq et al's data set were extrapolated onto the additional grid points on the SeaRISE standard grid using thin-plate radial basis functions. The accuracy of these extrapolated fields is not expected to effect the model results. The extension of the temperature and geothermal heat flux field used only the new data (pure extrapolation) but the bedrock topography also used interpolation of the bedrock topography field in the existing SeaRISE standard data set. All other fields provided by Le Brocq et al have a constant value along their edges and this constant value was used to fill the SeaRISE standard grid. For all fields, the data on the 1160x1120 grid provided by Le Brocq et al were copied directly with the exception that Le Brocq et al use a "fill value" of -9999 where data is missing in their accumulation and geothermal heat flux (Fox Maule et al only) fields but these values have been set to zero in the Antarctica developmental data set.

Additional fields provided by Le Brocq et al but not included in the SeaRISE developmental data set include various masks, lower ice surface elevations (including the one used to calculate ice thickness in the developmental data set), and a second topography field which includes more detail in the Recovery Basin adjacent to the Ronne Ice Shelf. This topography data was not included in the developmental data set due to scepticism of its accuracy.