Service Interruption

NASA Distributed Active Archive Center (DAAC) at NSIDC

ICESat / GLAS Data

Ice, Cloud, and land Elevation / Geoscience Laser Altimeter System


Description of Special Request ICESat/GLAS Files

Data from the ICESat/GLAS Data Subsetter is referred to as special request data. The data package you receive from the subsetter will contain a combination of various file types. The name for each file type begins with a special 2- or 3-character prefix, followed by the product identification number (01-15). You only need files beginning with GLA, which are the data files. All file types are described in the following table.

Prefix Description
GLA The data file in scaled integer binary format.
The bin file lists the geographic bins that the product traverses and the unique index numbers within the product that go through that bin. One bin file is required for each product. BNA is for altimetry data; BNL is for atmosphere (lidar) data. See BN file byte description.
The georeference file allows direct access to the start of each bin in the bin file. One georeference file is required for each bin file. GRA is for altimetry data; GRL is for atmosphere (lidar) data. See GR file byte description.
PS The pass file lists the passes present in the product file. One pass file is required for each product file. See PS file byte description.
UR The unique index file correlates the physical data record numbers with the unique index numbers in a product file. One unique index file is required for each product file. See UR file byte description.

The file naming convention for data files (GLA*) is illustrated in the following example:


GLA07 = Product ID
03022023 = Date (yymmddhh) of the beginning of the first granule that is used to create the subset
r1069 = Special request number (r indicates this is a special request)
428 = YXX release number
See ICESat/GLAS YXX Release Numbers for more information about the release number in file names.
L1 = Laser identifier (laser 1 in this example)
P0195 = Unique product set ID number
01 = "Part number" of file so multiple files can be created if a single file will exceed the 2 GB file size limit
00 = Version of this file (starting with 00)


Page last updated: 06/12/08