This map layer is a grid map of 2000 average vegetation growth for Alaska and the conterminous United States. The nominal
spatial resolution is 1 kilometer and the map layer is based on 1-kilometer AVHRR data. The data were compiled by staff at
the USGS Center for Earth Resources Observation and Science.
Citation
Title Average Vegetation Growth 2000 - Direct Download
publication Date
2005-12-01
presentationForm
mapDigital
cited responsible party
-
publisher
organisation Name
National Atlas of the United States
Contact information
Address
, Reston, VA
cited responsible party
-
originator
organisation Name
Center for Earth Resources Observation and Science, U.S. Geological Survey
These data are intended for geographic display and analysis at the continental level, and for large regional areas. The data
should be displayed and analyzed at scales appropriate for 1:2,000,000-scale data. No responsibility is assumed by the National
Atlas of the United States or the U.S. Geological Survey in the use of these data.
Resource language:
eng; USA
Resource progress code:
completed
Resource Maintenance Information
maintenance or update frequency:
irregular
Constraints on resource usage:
Constraints
Use limitation statement:
Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed
or implied is made by the U.S. Geological Survey regarding the utility of the data on any other system, nor shall the act
of distribution constitute any such warranty. No responsibility is assumed by the U.S. Geological Survey in the use of these
data.
Constraints on resource usage:
Legal Constraints
use constraint:
otherRestrictions
Other constraints
Use Constraints: None. Acknowledgment of the National Atlas of the United States of America would be appreciated in products
derived from these data.
Constraints on resource usage:
Legal Constraints
Access Constraints
otherRestrictions
Other constraints
Access Constraints: None
Spatial representation type code:
grid
Processing environment:
Native Dataset Environment: The original data were in 8-bit binary format. They were converted to GeoTIFF format for use in
the National Atlas Map Maker.
Resource extent
Geographic Extent
Geographic Bounding Box
westBoundLongitude
166
eastBoundLongitude
-4
northBoundLatitude
83
southBoundLatitude
15
Temporal Extent
2000-01-01
Additional information on resource:
This image is based on data recorded by the Advanced Very High Resolution Radiometer (AVHRR) sensors carried in Earth orbit
onboard several NOAA satellites. AVHRR data has a ground resolution of 1.1 kilometer and a swath width of over 2000 kilometers.
AVHRR imagery that covers the whole Earth is recorded every day, but the most commonly used AVHRR products are the composite
images that are created from AVHRR data every two weeks. Compositing two weeks of images means that data obscured by cloud
cover on any particular day can be replaced by data recorded on a clear day during the same period. Biweekly AVHRR composites
are the basis for Normalized Difference Vegetation Index (NDVI) calculations. The NDVI is a measure of vegetation cover and
plant growth. NDVI is calculated from AVHRR channel 2 (near-infrared) and channel 1 (visible, red light) by this formula:
NDVI = (channel 2 - channel 1) / (channel 2 + channel 1). Because they indicate vegetation vigor, NDVI values are commonly
called "greenness data." Greenness composites have been produced for the conterminous United States every two weeks since
1989, and for Alaska, during the growing season, since 1990. Average greenness is derived by examining all the composites
for a year and calculating the arithmetic average of all the biweekly NDVI values for each pixel. The National Atlas includes
peak and average greenness images for each year from 1990 to 2004. For more information on NDVI, AVHRR, and greenness datasets,
see <http://eros.usgs.gov/greenness/>. A basic explanation of AVHRR can be found at <http://nationalatlas.gov/articles/mapping/a_avhrr.html>.
The following table describes the display of vegetation growth in the TIFF image: >Value Description RGB values >_________________________________________________________
>1 No data 132 158 172 >2 Water 132 193 255 >100-110 Less vigorous growth 187 126 99 >111-115 | 226 168 109 >116-125 | 244
205 120 >126-133 | 239 233 164 >134-142 | 254 251 172 >143-150 | 217 233 172 >151-158 | 178 214 137 >159-166 | 137 196 104
>167-174 | 127 172 119 >175-200 More vigorous growth 99 144 76 > The associated world file is included as part of the GeoTIFF.
The contents of the world file are: >1000.0000 >0.000000 >0.000000 >-1000.0000 >-6086629.0000 >4488761.0000 The following
projection file can be used when using ESRI's ArcGIS to view the GeoTIFF (any line breaks should be removed): PROJCS["NAD_1983_Lambert_Azimuthal_Equal_Area",GEOGCS
["GCS_Sphere_ARC_INFO",DATUM["D_Sphere_ARC_INFO",SPHEROID ["Sphere_ARC_INFO",6370997.0,0.0]],PRIMEM["Greenwich",0.0], UNIT["Degree",0.0174532925199433]],PROJECTION
["Lambert_Azimuthal_Equal_Area"],PARAMETER["False_Easting",0.0], PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",
-100.0],PARAMETER["Latitude_Of_Origin",45.0],UNIT["Meter",1.0]]
point of contact
-
pointOfContact
individual Name John Hutchinson
organisation Name
SAIC
Contact information
Telephone
Voice 605-594-6049
Address
USGS Center for EROS, Sioux Falls, SD, 57198-0001
Country USA
descriptor Values for greenness pixels range from 100 to 200. Lower values indicate areas of barren to sparsely vegetated land. Higher
values indicate areas of vegetation, with the highest values indicating areas of abundant, healthy vegetation.
organisation Name
Earth Science Information Center, U.S. Geological Survey
Contact information
Telephone
Voice 1-888-ASK-USGS (1-888-275-8747)
Voice 703-648-5920
Address
507 National Center, Reston, VA, 20192
contact Instructions
In addition to the address above there are other ESIC offices throughout the country. A full list of these offices is at <http://ask.usgs.gov/esic_index.html>.
notes: This metadata was automatically generated from the FGDC Content Standards for Digital Geospatial Metadata standard (version
FGDC-STD-001-1998) using the 2012-06-20T17:21:00 version of the FGDC RSE to ISO 19115-2 transform.
Metadata Constraints
Security Constraints
Classification
unclassified
Classification
System None
Metadata contact
-
pointOfContact
individual Name Peg Rawson
organisation Name
National Atlas of the United States
Contact information
Telephone
Voice 703-648-4183
Address
12201 Sunrise Valley DriveMS-561, Reston, VA, 20192