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South America Characteristics

SOUTH AMERICA LAND COVER CHARACTERISTICS DATA BASE

PLEASE NOTE: This is the Version 1.2 release of the South America land cover characteristics data base. It has not yet been validated and is subject to review. Following validation, the data base will be modified based on the lessons learned. Comments from users of this data set are encouraged and will be considered for incorporation in later versions. Please email comments to:

lcac@usgs.gov

Table of Contents

• 1.0 Data Description
• 1.1 Anonymous FTP for UNIX or PC Users
• 1.2 Downloading from the World Wide Web Site
• 2.0 Geometric Characteristics
• 2.1 Interrupted Goode Homolosine Projection Parameters
• 2.2 Lambert Azimuthal Equal Area Projection Parameters
• 3.0 File Listing
• 4.0 Derived Data Sets
• 4.1 South America Seasonal Land Cover Regions Legend
• 4.2 Global Ecosystems Legend
• 4.3 IGBP Land Cover Legend
• 4.4 USGS Land Use/Land Cover System Legend
• 4.5 Simple Biosphere Model Legend
• 4.6 Simple Biosphere 2 Model Legend
• 4.7 Biosphere-Atmosphere Transfer Scheme Legend
• 5.0 References

1.0 Data Description

The South America land cover data base is one portion of a global land cover characteristics data base that is being developed on a continent-by-continent basis. All continents in the global data base share the same map projections (Interrupted Goode Homolosine and Lambert Azimuthal Equal Area), have 1-km nominal spatial resolution, and are based on 1-km AVHRR data spanning April 1992 through March 1993. Each continental data base has unique elements that are based on the salient geographic aspects of the specific continent. In addition, a core set of derived thematic maps produced through the aggregation of seasonal land cover regions are included in each continental data base. These are:

• Global Ecosystems (Olson, 1994a, 1994b)
• IGBP Land Cover Classification (Belward, 1996)
• U.S. Geological Survey Land Use/Land Cover System (Anderson and others, 1976)
• Simple Biosphere Model (Sellers and others, 1986)
• Simple Biosphere 2 Model (Sellers and others, 1996)
• Biosphere-Atmosphere Transfer Scheme (Dickinson and others, 1986)

The legends for each of these derived data sets can be found in Section 4.2 - 4.7.

For a description of the methodology for the global data base, see the global readme file found under the LP DAAC home page (http://LPDAAC.usgs.gov/glcc/glcc.php).

The South America land cover characteristics data are in a flat, headerless raster format. The pixel values correspond to class numbers defined in the appropriate land cover classification scheme legend. Data are distributed as compressed and uncompressed single-band images. The files can be obtained either by anonymous file transfer protocol (ftp) or downloaded from the LP Distributed Active Archive Center (DAAC) World Wide Web site: (http://LPDAAC.usgs.gov/glcc/sa_int.php). The instructions for accessing these files are contained in the following two sections.

1.1 Anonymous FTP for PC or UNIX Users

1. Contact the FTP server. At your command prompt, use the command: ftp edcftp.cr.usgs.gov
2. Login as an anonymous user and use your email address as the password.
3. Change to the directory pub/data/glcc
4. Change to the South America subdirectory, sa
5. Change to the directory for the projection of interest (i.e., goode for Interrupted Goode Homolosine projection or lambert for Lambert Azimuthal Equal Area Projection).
6. Locate the file of interest (a complete file listing is located in section 3.0 of this readme). The image files were compressed using the GNU 'gzip' software and can be identified by the ".gz" file extension. These files must be uncompressed before use with the 'gunzip' utility, a part of the 'gzip' software. Directions for acquiring the gzip software from GNU can be found on the WWW on the GNU home page (http://www.gnu.org/). If you do not have access to gzip, the ftp server can uncompress the files as they are retrieved.
7. To FTP compressed files:
• Use the FTP command 'binary' to transfer image data.
• Use the FTP command 'get' followed by the file name. Include the .gz extension to receive as a compressed file (e.g., get sabats1_2.img.gz).
8. To FTP uncompressed files:
• Use the FTP command 'binary' to transfer image data.
• Use the FTP command 'get' followed by the file name without the .gz extension to transfer an uncompressed file (e.g., get sabats1_2.img). Please note that the uncompressed files are typically many times larger than the compressed versions and therefore will take much longer to transmit.

1.2 Downloading from the World Wide Web Site

From the South America Land Cover page, select either data in Interrupted Goode Homolosine projection or data in Lambert Azimuthal Equal Area projection. The selection will link to a page that contains links to all documentation files and the image files (both compressed and uncompressed). NOTE: World Wide Web browsers can vary in how the files will be downloaded. On PCs, some browsers will allow a user to interactively select the location where the file will be saved and to edit the file name. However, on certain browsers files may be automatically downloaded to a default storage location on the local system.

1. Select either button, compressed or uncompressed, for the file of interest.
2. A pop-up screen may appear, showing information on the download procedure. At this point, choose the directory in which to save the file.
3. For compressed files, the .gz extension must be added to the filename before downloading. However, if the browser will not accept adding an extension, continue with the download, and then rename the file with the .gz extension when the download is complete.
4. For uncompressed files, leave the .gz extension off. If a pop-up screen shows the filename with a .gz extension either edit the filename, or proceed with the download and rename the file without the extension after the procedure is complete.

2.0 Geometric Characteristics

The South America data base is available in two different map projections: the Interrupted Goode Homolosine and the Lambert Azimuthal Equal Area (see Steinwand, 1994 , and Steinwand and others, 1995, for a complete description of these projections).

2.1 Interrupted Goode Homolosine Projection Parameters

The data dimensions of the Interrupted Goode Homolosine projection for the South America land cover characteristics data set are 8,016 lines (rows) and 5,632 samples (columns) resulting in a data set size of approximately 45 megabytes for 8-bit (byte) images. The following is a summary of the map projection parameters used for this projection:

Projection Type: Interrupted Goode Homolosine

Units of measure: meters

Pixel Size: 1000 meters

Radius of sphere: 6370997 m

XY corner coordinates (center of pixel) in projection units (meters):


Lower left: ( -9276000, -6385000)

Upper left: ( -9276000, 1630000)

Upper right: ( -3645000, 1630000)

Lower right: ( -3645000, -6385000)

2.2 Lambert Azimuthal Equal Area Projection Parameters

The data dimensions of the Lambert Azimuthal Equal Area projection for the South America land cover characteristics data set are 8,000 lines (rows) and 6,000 samples (columns) resulting in a data set size of approximately 48 megabytes for 8-bit (byte) images. The following is a summary of the map projection parameters used for this projection:

Projection Type: Lambert Azimuthal Equal Area

Units of Measure: meters

Pixel Size: 1000 meters

Radius of sphere: 6370997 m

Longitude of origin: 60 00 00 W

Latitude of origin: 15 00 00 S

False easting: 0.0

False northing: 0.0

XY corner coordinates (center of pixel) in projection units (meters):

Lower left: ( -3000000, -4899000)

Upper left: ( -3000000, 3100000)

Upper right: ( 2999000, 3100000)

Lower right: ( 2999000, -4899000)

3.0 File Listing

4.0 Derived Data Sets

4.1 South America Seasonal Land Cover Regions Legend

South America, v. 1.2

4.2 Global Ecosystems Legend

4.3 IGBP Land Cover Legend

4.4 USGS Land Use/Land Cover System Legend (Modified Level 2)

4.5 Simple Biosphere Model Legend

4.6 Simple Biosphere 2 Model Legend

4.7 Biosphere-Atmosphere Transfer Scheme Legend

5.0 References

Anderson, J.R., Hardy, E.E., Roach J.T., and Witmer R.E., 1976, A land use and land cover classification system for use with remote sensor data: U.S. Geological Survey Professional Paper 964, 28 p.

Belward, A.S., ed., 1996, The IGBP-DIS global 1 km land cover data set (DISCover)-proposal and implementation plans: IGBP-DIS Working Paper No. 13, Toulouse, France, 61 p.

Dickinson, R.E., Henderson-Sellers, A., Kennedy, P.J., and Wilson, M.F., 1986, Biosphere-atmosphere transfer scheme (BATS) for the NCAR community climate model: NCAR Technical Note NCAR/TN275+STR, Boulder, CO. 69 p.

Olson, J.S., 1994a, Global ecosystem framework-definitions: USGS EROS Data Center Internal Report, Sioux Falls, SD, 37 p.

_____ 1994b, Global ecosystem framework-translation strategy: USGS EROS Data Center Internal Report, Sioux Falls, SD, 39 p.

Sellers, P.J., Mintz, Y., Sud, Y.C., and Dalcher A., 1986, A simple biosphere model (SiB) for use within general circulation models: Journal of Atmospheric Science, v. 43, p. 505-531.

Sellers, P.J., Randall, D.A., Collatz, G.J., Berry, J.A., Field, C.B., Dazlich, D.A., Zhang, C., Collelo, G.D., and Bounoua, L., 1996, A revised land surface parameterization (SiB2) for atmospheric GCMs - Part I-model formulation: Journal of Climate, v. 9, p. 676-705.

Steinwand, D.R., 1994, Mapping raster imagery to the Interrupted Goode Homolosine projection: International Journal of Remote Sensing, v. 15, no. 17, p. 3,463-3,472.

Steinwand, D.R., Hutchinson, J.A., and Snyder, J.P. ,1995, Map projections for global and continental data sets and an analysis of pixel distortion caused by reprojection: Photogrammetric Engineering and Remote Sensing, v. 61, p. 1,487-1,497.