Normalized Difference Vegetation Index (NDVI) for the SGP97 Region Derived from Landsat Thematic Mapper Data
NDVI Data NDVI Map Vegetation page
Overview
The Normalized Difference Vegetation Index (NDVI) is widely used in a variety of biospheric and hydrologic studies. For instance the NDVI plays an important role in the ESTAR soil moisture mapping conducted in SGP97 (http://disc.gsfc.nasa.gov/fieldexp/SGP97/estar.html).
NDVI standard products are readily available from several sources. These are all based upon data collected by the NOAA AVHRR instrument. There are a variety of products with varying temporal and spatial resolutions (http://www2.ncdc.noaa.gov:80/docs/gviug/). 10 day and longer interval products are generated in order to have cloud free coverage. The maximum resolution of the AVHRR products is 1 km, however, much of the archived data is at a coarser resolution (8 km).
As part of SGP97, a Landsat Thematic Mapper, TM, scene from July 25, 1997 was acquired. This was used to produce a high resolution (30 m) NDVI data set. This data set should be used with the recognition that it represents a single point in time and was obtained just after the SGP97 experiment.
The Data
The TM image used was acquired on July 25, 1997. A scene was also available for July 9, 1997 but had a considerable amount of cloud cover. These data sets were obtained to support the land cover classification described in http://disc.gsfc.nasa.gov/fieldexp/SGP97/oklarev.html.
The original TM image was georegistered but no radiometric corrections were made. NDVI was computed for each pixel using the following equation
NDVI = Band 4 - Band 3
Band 3 + Band 4Values of NDVI will range from -1 to +1 and vegetated areas will typically have values greater than zero.
Specifications
The data product produced here was an 8 bit binary. In order to maximize the dynamic range the following scaling was performed
Scaled NDVI = 100(NDVI + 1) The geographic description of the data set is as follows:
Specifications of the classified image Projection: Universal Transverse Mercator Zone 14 Earth Ellipsoid Clarke 1866 (NAD 27) Upper Left Corner 464385.000 E 4253715.000 N Upper Right Corner 758685.000 E 4253715.000 N Lower Left Corner 464385.000 E 3723015.000 N Lower Right Corner 758685.000 E 3723015.000 N Pixel Size 30.000 E 30.000 N Upper Left Corner 99d24'28.98" W Lon 38d25'58.27" N Lat Upper Right Corner 96d02'16.75" W Lon 38d23'46.02" N Lat Lower Left Corner 99d23'02.67" W Lon 33d38'53.26" N Lat Lower Right Corner 96d12'42.24" W Lon 33d37'02.20" N Lat Note The lower right corner of NDVI image does not coincide with the lower right corner of land cover image. The NDVI image is slightly smaller, 30 pixels in both the east west and north south directions.
The Files
File Name and Format Information
File name File type Format Description File size Storage required ndvi725.bil binary consistency
BYTEORDER M LAYOUT BIL NROWS 17690 NCOLS 9810 NBANDS 1 NBITS 8 NDVI for the SGP 97 study area ~165.5MB ~166MB ndvi.tif binary tiff image Image of NDVI for SGP97 study region ~235KB ndvi.doc Document Microsoft Word explanation of the procedures used to create the classification as well as class description and accuracy assesment. ~31KB ndvi.txt ascii text ~5KB
Data Access and Contacts
The SGP97 NDVI data is available in the following GES DISC ftp site:
The principal investigator for the NDVI data set is
Tom Jackson
USDA ARS Hydrology Lab
Bldg. 007, Rm. 104, BARC-West
Beltsville, MD 20705 USA
E-mail : tjackson@hydrolab.arsusda.gov
Voice: (301) 504-8511
Fax: (301) 504-8931For more information using NDVI data from GES DISC, contact:
Edee Ocampo
Goddard Earth Sciences Data and Information Services Center (GES DISC)
Code 610.2
NASA Goddard Space Flight Center
Greenbelt, Maryland 20771
E-Mail:Edee.Ocampo@nasa.gov
Voice: 301-614-5376
Fax: 301-614-5268
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Last update:Thu Jan 28 09:34:12 EST 1999
Page Author: Hydrology Data Support Team -- hydrologydisc@listserv.gsfc.nasa.gov Website Curator: Anthony Drake-- web-contact-disc@listserv.gsfc.nasa.gov NASA official: Steve Kempler, DAAC Manager -- Steven.J.Kempler@nasa.gov |