This readme file will address the following:

	1) Contents of the zip file
	2) General overview
	3) Suggestions about "how to work" with these files


1) Contents of the zip file:

	Files in this zip file are:
		Geotiff - Full resolution of this file -  (~ 26 Megabytes)
		Geotiff - Lower resolution of the Full resolution image (~ 6 Megabytes)
		World header file (for the above GeoTiff files with a .tfw extension
				   - enables georeferencing)
		Readme file - Filename.txt
		FGDC Metadata file - class.html

	The actual file names are:

		nlcd_class83.tfw			(World header file)
		nlcd_class83.tif.gz			(Full Resolution)
		nlcd_class83_low_res.tfw		(World header file)
		nlcd_class83_low_res.tif.gz		(Lower Resolution)
		nlcd_class83.txt			(Readme file)
		class.html				(FGDC)

	The full resolution file contains integer images in an Albers
	projection with the following characteristics:

		Number of Lines:  2910
		Number of Samples: 4626
		Number of Bands:   1
		Upper left corner of Upper Left Pixel:  -2362000, 3178000
		Pixel size 1000 m

	Projection information:

        	  Albers Conical Equal Area Projection
	          Datum NAD 83
	          Spheroid  GRS1980
	          Units Meters
	          1st Standard Parallel              29  30  0.00
	          2nd Standard Parallel              45  30  0.00
	          Central meridian                  -96  0   0.00
	          Latitude of projection's origin:   23  0   0.00

	The lower resolution file (filename_low_res.tif) contains integer images in an Albers
	projection with the following characteristics:

		Number of Lines:  1455
		Number of Samples: 2313
		Number of Bands:   1
		Upper left corner of Upper Left Pixel:  -2362000, 3178000
		Pixel size 2000 m

	Projection information:

	          Albers Conical Equal Area Projection
	          Datum NAD 83
	          Spheroid  GRS1980
	          Units Meters
	          1st Standard Parallel              29  30  0.00
	          2nd Standard Parallel              45  30  0.00
	          Central meridian                  -96  0   0.00
	          Latitude of projection's origin:   23  0   0.00
2) General Overview:

	nlcd_class83.tif	 Small Grains - Areas used for the production of
				 graminoid crops such as wheat, barley, oats, and rice.

			         Image of land cover classification produced by the
        	                 USGS National Land Cover Characterization Project,
                	         acquired from Landsat TM for years near 1992.
                        	 A more complete description can be obtained at
	                         (http://landcover.usgs.gov/natlandcover.html).

        	                 The classification key (21 classes) can be obtained
                	         at (http://landcover.usgs.gov/classes.html).

        	                 Pixel values range from 0 to 10,000.  The percent
                	         area estimate was multiplied by 100 to keep data
                        	 precision (e.g. 9876 means 98.76%).

	For more information on the EPA land cover site (MRLC) see the below url:
		http://www.epa.gov/mrlc/nlcd.html

3) Suggestions on "How to Work" with these files:

	TAR AND ZIP INFORMATION:

		UNIX:
		On Unix and Linux extract and unzip the files.
		The zip file has been zipped with gzip.
		(use Unix "man pages" if you're not fimiliar with "how to do" this)

		MICROSOFT WINDOWS
		On Windows use "Winzip classic" to untar and unzip the files.
		The zip file has been zipped with gzip.

	IMAGE SIZE:

		THE FULL RESOLUTION IMAGE FILES ARE VERY LARGE IN SIZE -
		MAKE SURE YOU HAVE ENOUGH DISK SPACE BEFORE UNZIPPING THEM.

	IMAGE VIEWERS VS DATA VIEWERS:

		Image viewers have the ability to view the file, (one can
		see a pretty picture), but the end user will not be able to
		get data values.

		For viewing files and querying the data values use software
		such as listed below in the Data Viewing software section.

	IMAGE VIEWING SOFTWARE:

		Photoshop - If some images appear black in Photoshop, you will need
			    to increase the Brightness/Contrast to view the correct
			    representation of the image.
		Arc Explorer
		Other imaging software

		Image viewers might be unable to open up the full resolution
		Geotiff file. You will need alot of RAM or have	your image package
		set up to use all your computer resources to be able to open these files.

	DATA VIEWING SOFTWARE:
		(We recommend using these or similiar products to query the data)

		ERDAS
		ENVI
		PCI
		Idrisi
		ArcMap
		ArcInfo
		Arc View (Convert image to a grid in ArcInfo then use the Spatial
			  Analyst extension in Arc View - also the end user can use
			  the "Image Analyst" extension to view the image files).

		How to load images in ArcView 3.X:
		___________________________________________________________________
		Start ArcView
		File->extensions-> turn on tiff extensions (click tiff checkbox)
		(if you have Spatial Analyst turn that extension on)
		Click the View "new" button
		Select the pull down "view"
		Select "add theme"
		Change the data source type from "Feature data source"
			to "Image data source" then select the tif.

___________________________________________________________________

If you have any questions regarding the data or the file formats,
please contact:

       	         Patrick Hayes
                 Solar-Terrestrial Physics Division
                 NOAA National Geophysical Data Center
                 325 Broadway E/GC2
	         Boulder, CO 80305
	         Tel: 303-497-6764   Fax: 303-497-6513
	         email: Patrick.J.Hayes@noaa.gov