30 arc-second DEM for Antarctica

LR = 0W, 90S (3600 rows x 10800 columns) -ant_dem_1kms3 UL = 0 W, 60S. LR = 90E, 90S (3600 rows x 10800 columns) -ant_dem_1kms4 UL = 90 E, 60S. LR = 180E, 90S (3600 rows x 10800 columns) Antarctic DEM in polar stereographic coordinates (meters) -ant_dem_1kmps UL = -2700000 x 2699000.

LR = 2699000 x -2700000 (5400 rows x 5400 columns)

Note

Both DEMs are referenced to the WGS84 ellipsoid. The standard latitude of the polar stereographic DEM is 71S, and it central meridian is 0. Data Organization: Data are distributed as 16-bit straight raster image files in a latitude/ longitude coordinate system, and also in a polar stereographic coordinate system.

Image files are identified by the .bil.gz extension. Each image file of the Antarctica data set is compressed using the GNU "gzip" utility. If you do not have access to gzip, the FTP server will uncompress the file as you retrieve it.

To do this, simply leave off the ".gz" extension when retrieving the file (NOTE: This option is not available through MOSAIC). For example, to retrieve the file "af_1k_dem1.bil.gz" without compression just use "get af_dem_lks1.bil". Note that the uncompressed files are typically five times larger than the compressed versions and so will take five times longer to transmit.

The gzip program is available via anonymous FTP at the following sites: prep.ai.mit.edu:/pub/gnuwuarchive.wustl.edu:/systems/gnu Each image file is accompanied by five ancillary files (header file, world file, statistics file, coordinate file, and data descriptor record ). The format of each ancillary file is described below: