The olson_lba.dat.gz file contains a subset of Olson's Major World Ecosystem 
Complexes Ranked by Carbon in Live Vegetation: A Database. The subset is for the 
LBA study area.

This README file contains information regarding:
1.  Data format
2.  Procedure used to create the Amazon subset
3.  Legend and data source

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DATA FORMAT
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The downloadable file, olson_lba dat.gz, is a UNIX compressed file.

The data file is in ASCII Grid format for ArcInfo.  The file contains a single 
ASCII array with integer values. Coordinates listed below are in decimal 
degrees.

Rows 70
Columns 110
UpLeftX -85
UpLeftY 10
LoRightX -30
LoRightY -25
cellsize 0.5
Projection geographic

The ASCII file consists of header information containing a set of keywords, 
followed by cell values in row-major order. The file format is

<NCOLS xxx>
<NROWS xxx>
<XLLCORNER xxx>
<YLLCORNER xxx>
<CELLSIZE xxx>
{NODATA_VALUE xxx}
row 1
row 2
.
.
.
row n

where xxx is a number, and the keyword NODATA_VALUE is optional and defaults to 
-9999.  Row 1 of the data is at the top of the grid, row 2 is just under row 1 
and so on.  The end of each row of data from the grid is terminated with a 
carriage return in the file. 

Although the nodata_value is set to -9999 in the header that value does not 
actually occur in the data.  To import this file into ArcInfo use the following 
command at an ARC prompt:

ASCIIGRID <in_ascii_file> <out_grid> {INT | FLOAT}

Arguments
<in_ascii_file> - the ASCII file to be converted. 
<out_grid> - the name of the grid to be created.
{INT | FLOAT} - the data type of the output grid.
INT - an integer grid will be created.
FLOAT - a floating-point grid will be created.

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PROCEDURE USED TO CREATE THE AMAZON SUBSET
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The original data were converted to an ArcInfo grid using the ASCIIGRID command.  
Using GRID ( a raster- or cell-based geoprocessing toolbox that is integrated 
with ArcInfo) the SETWINDOW command was used to define the subarea of interest.  
This subarea was defined by identifying the bounding coordinates as follows: 

x_min -85     y_min -25     x_max -30     y_max 10

The "snap_grid" option of the SETWINDOW command was used.  This snaps the lower-
left corner of the specified window to the lower-left corner of the nearest cell 
in the snap_grid and snaps the upper-right corner of the specified window to the 
upper-right corner of the nearest cell in the snap_grid.  In this case the 
snap_grid was the original data grid.  The purpose of this is to ensure the 
proper registration of the newly set analysis window.  The command format used 
is as follows:

SETWINDOW x_min y_min x_max y_max original_grid

Once the window was set, creating the new grid was simply a matter of setting 
the new subset grid equal to the original grid.

subset_grid = original_grid
                                                                                                                                               
An ASCII array was created from the new subset grid using the GRID command 
GRIDASCII.

file.dat = GRIDASCII(subset_grid)

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LEGEND & ADDITIONAL SOURCES OF INFORMATION
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For legend information please refer to the following web page:
http://cdiac.esd.ornl.gov/ftp/ndp017/table.html

Although not all of the global categories may be represented in the subset of 
the data, the original legend has been retained.

The original data and documentation can be obtained through the Carbon Dioxide 
Information Analysis Center (CDIAC) at Oak Ridge National Laboratory (ORNL)
World Wide Web site: http://cdiac.esd.ornl.gov/

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ORIGINAL DATA SET CITATION
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Olson, J.S., J.A. Watts, and L.J. Allison, 1985. Major World Ecosystem Complexes 
Ranked by Carbon in Live Vegetation.  NDP017, Carbon Dioxide Information Center, 
Oak Ridge National Laboratory, Oak Ridge, Tennessee. Data available online at 
http://cdiac.esd.ornl.gov/ndps/ndp017.html 


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SUBSET DATA SET CITATION
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LBA Subset of Olson, J.S., J.A. Watts, and L.J. Allison, 1985. Major World 
Ecosystem Complexes Ranked by Carbon in Live Vegetation.  NDP017, Carbon Dioxide 
Information Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee. Data 
available online at Available on-line at ftp://www-
eosdis.ornl.gov/data/lba_regional/olson