Amazon Basin Subset of 1 km NDVI composite data from the NOAA AVHRR satellites in monthly time steps for the period of April 1992-March 1993

Summary:

The dataset consists of a northern South American continental subset of the 1 km resolution Normalized Difference Vegetation Index (NDVI) composites developed by the Global Land Cover Characterization (GLCC) project underway at the US Geologic Survey's (USGS) EROS Data Center (EDC). The dataset spans a twelve month time series from April 1992-March 1993.

1. Data Set Overview

Data Set Identification:
Amazon Basin Subset of 1 km NDVI composite data from the NOAA AVHRR satellites in monthly time steps for the period of April 1992-March 1993
Data Set Introduction:
Twelve monthly 1 km resolution continental NDVI composite images were made available as layers of the preliminary release of the South American continental portion of the Global Land Cover Characterization project underway at the USGS/EROS Data Center. A portion of each of these continental time slices has been subset for use with the NASA Large Biosphere-Atmosphere (LBA) experiment in the Amazon Basin. The dataset spans a twelve month time period from April 1992-March 1993.
Objective/Purpose:
Not Available
Summary of Parameters:
NDVI - Increasing positive values indicate increasing green vegetation and negative values indicate nonvegetated surface features such as water, barren, ice, and snow or clouds.
Discussion:
Not Available
Related Data Sets:
Each continent of the global land cover characteristics data base are in a flat, headerless raster format. Each raster image contains class number values for each pixel that correspond to the appropriate land cover classification scheme legend. Data are distributed as compressed and uncompressed single-band images located on the EROS Data Center (EDC) anonymous file transfer protocol (ftp) site and accessible from the EDC Distributed Active Archive Center (DAAC) World Wide Web site Continental GLCC Data (http://edcwww.cr.usgs.gov/landdaac/glcc/glcc.html).
Available continents (as of 8-13-97) are: Africa, North America, and South America

2. Investigator(s)

Investigator(s) Name and Title:
Eidenshink, J.C., M.S, and Loveland, T., M.S.; Peter Schlesinger, M.A., Daniel Nepstad, Ph.D., Paul Lefebvre, M.S.
Title of Investigation:
Source Data Title:
Global Land Cover Characteristics Database
Data Preparation Title:
Land-use in Amazonia and the Cerrado of Brazil: State of Knowledge and GIS Database
Contact Information:
1) Source Data Investigator:
Jeff Eidenshink / Tom Loveland
Data Services Branch
USGS/EROS Data Center
Sioux Falls, SD 57198
Phone: 605-594-6116
Fax: 605-594-6963
Email: edc@eos.nasa.gov
2) Data Preparation Investigators:
Peter Schlesinger / Dan Nepstad / Paul Lefebvre
Woods Hole Research Center
PO Box 296, 149 Woods Hole Rd.
Woods Hole, MA 02543
Phone: (508)540-9900
Fax: (508)540-9700
Email: pschles@whrc.org

3. Theory of Measurements

Not Available

4. Equipment

Sensor/Instrument Description:

AVHRR
Advanced Very High Resolution Radiometer (AVHRR) is a broad-band, 4 or 5 channel (depending on the model) scanner, sensing in the visible near-infrared, and thermal infrared portions of the electromagnetic spectrum. This sensor is carried on NOAA's Polar Orbiting Environmental Satellites (POES) beginning with TIROS-N in 1978.

The AVHRR sensor provides for global (pole to pole) on board collection of data from all spectral channels. Each pass of the satellite provides a 2399 km (1491 mi) wide swath. The satellite will orbit the earth 14 times each day from 833 km (517 mi) above its surface

Collection Environment:
Not Available
Source/Platform:
Not Available
Source/Platform Mission Objectives:
Not Available
Key Variables:
Not Available
Principles of Operation:
Not Available
Sensor/Instrument Measurement Geometry:
Not Available
Manufacturer of Sensor/Instrument:
Not Available
Calibration:
Specifications:
Not Available
Tolerance:
Not Available
Frequency of Calibration:
Not Available
Other Calibration Information:
Not Available

5. Data Acquisition Methods

The source data for these subsets were acquired by anonymous FTP from the site: edcftp.cr.usgs.gov, in the directory: /pub/data/glcc/sa/lambert/ndvimon

6. Observations

Data Notes:
Not Available
Field Notes:
Not Available

7. Data Description

Spatial Characteristics:
Spatial Coverage:
Location
Min X -3000000
Max X 2999000
Min Y -556542.9
Max Y 3100000
In decimal degrees of Longitude and Latitude
Spatial Coverage Map:
Not Available
Spatial Resolution:
1000 meters
Projection:
Lambert Azimuthal Equal Area
Grid Description:
Rows 3657
Columns 6000
Temporal Characteristics:
Temporal Coverage:
Text
Year Week
1982 (Beginning of First Generation product 12 April, week 15)
Temporal Coverage Map:
Each of the images correspond to the monthly NDVI composites of the period of April 1992 through March 1992
Temporal Resolution:
Not Available
Data Characteristics:
Parameter/Variable:
Scaled NDVI
Variable Description/Definition:

NDVI is computed by calculating the ratio of the VI (vegetation index, i.e., the difference between Channel 2 and 1) and the sum of Channels 2 and 1. Thus NDVI = (channel 2 - channel 1) / (channel 2 + channel 1), producing values in the range of -1.0 to 1.0.

To obtain the most precision, the NDVI is derived from calibrated channels 1 and 2 data in 16-bit precision, prior to geometric registration and resampling (Eidenshink and Faundeen, 1994).

The computed NDVI is then scaled to an 8- bit range to minimize data volume for analysis and display.

Unit of Measurement:
Scaled NDVI
Data Source:
The Amazon Basin subset data in this data set is immediately derived from the time series released by the GLCC at USGS EDC. Those original data were derived from 10-day composites of 1-km Advanced Very High Resolution Radiometer (AVHRR) data spanning a 12-month period (April 1992-March 1993) (see Eidenshink and Faundeen, 1994).
Data Range:
The NDVI have been scaled from the range of -1.0 to 1.0 as 0 to 200, where each value represents 1.0 percent of the total possible range (Eidenshink and Faundeen, 1994).
Sample Data Record:
Not Applicable

8. Data Organization

Data Granularity:

A general description of data granularity as it applies to the IMS appears in the EOSDIS Glossary.

Due to a data re-distribution agreement with USGS/EROS Data Center, the granularity of this data set consists of a single tarred and GNU-zipped file (WAMONNDL.TAZ) comprising 95,997,578 8-bit bytes.

Data Format:

Once uncompressed, the tarred and GNU-zipped file contains 12 flat binary raster image files, made up of 6000 columns by 3657 rows comprising 21,942,000 8-bit bytes, and 12 associated ASCII documentation files. The image files have no headers, trailers, or delimiters.

The structure of the documentation files is as follows (portions have been copied directly from the IDRISI for Windows v. 2.0 Help System, with the permission of the IDRISI Project, Clark University, Worcester, MA):

ITEM DESCRIPTION
title A descriptive name of the file.
data type The type of numbers stored in the file. Allowable entries are byte, integer and real.
file type The format in which the Image file is stored.
columns The number of columns in the image.
rows The number of rows in the image.
ref. system The name of the geographic referencing system used with the file.
ref. units The unit of measure used in the specified reference system. Allowable entries are m, ft, mi, km, deg and radians.
unit dist The scaling factor between the given coordinates and actual measurements on the ground.
min X The minimum X coordinate (left edge) of the image.
max X The maximum X coordinate (right edge) of the image.
min Y The minimum Y coordinate (bottom edge) of the image.
max Y The maximum Y coordinate (top edge) of the image.
pos'n error A measure of the accuracy of the positions in the image.
resolution The inherent resolution of the image. In most cases, this should correspond to the result of dividing the range of reference coordinates in X by the number of columns in the image.
min value The minimum value in the image.
max value The maximum value in the image.
value units The unit of measure of the values in the image. The term classes is used for all qualitative data sets, and that whenever standard linear units are appropriate, that the same abbreviations that are used for reference units should also be used (m, ft, mi, km, deg, rad).
value error This field records the error in the data values that appear in image cells. For qualitative data, this should be recorded as a proportional error. For quantitative data, the value here should be an RMS error figure.
flag value Any value in the image that is not a data value, but rather has a special meaning. If there is no flag value, this entry should remain blank.
flag def'n Definition of the above flag value. The most common data flags are those used to indicate background cells and missing data cells.
legend cats The number of legend categories present.
lineage Description of the history by which the values were recorded/derived.
completeness The degree to which the values describe the subject matter indicated.
consistency The logical consistency of the file.

9. Data Manipulations

Formulae:
Derivation Techniques and Algorithms:
Not Available
Data Processing Sequence:
Processing Steps:
Each of the monthly datafiles in this dataset were subset using the IDRISI for Windows geographic analysis system (Eastman, 1997) to include only the columns 0-5999 and rows 0-3656 [where the column/row coordinate of the upper left is (0,0)].
Processing Changes:
Not Available
Calculations:
Special Corrections/Adjustments:
Not Available
Calculated Variables:
Not Available
Graphs and Plots:
Not Available

10. Errors

Sources of Error:
Not Available
Quality Assessment:
Data Validation by Source:
While no data quality assessment was carried out specifically on the data in this Amazon Basin subset, a data quality evaluation for the original data was conducted and is reported by Zhu and Yang (1996).
Confidence Level/Accuracy Judgement:
Not Available
Measurement Error for Parameters:
Not Available
Additional Quality Assessments:
Not Available
Data Verification by Data Center:
Not Available

11. Notes

Limitations of the Data:
Not Available
Known Problems with the Data:
Not Available
Usage Guidance:
General USGS Disclaimer (at site of source data):
Some U.S. Geological Survey (USGS) information accessed through this page may be preliminary in nature and presented without the approval of the Director of the USGS. This information is provided with the understanding that it is not guaranteed to be correct or complete and conclusions drawn from such information are the responsibility of the user.
Any Other Relevant Information about the Study:
Not Available

12. Application of the Data Set

Major applications of AVHRR data include mapping fire fuels information, monitoring vegetation conditions and trends, producing image maps of large areas such as countries or continents, regional and continental snow cover mapping, conducting soil moisture analysis, and observing sand-storms and volcanic eruptions worldwide. NDVI data are used to analyze vegetative seasonality and landcover, and to help in the prediction of eco-climatic stress in drought prone regions.

13. Future Modifications and Plans

Not Available

14. Software

Software Description:
Two softwares are required to read the files in this dataset:
the shareware tar program tar.exe
the GNU compression utility gzip.exe
Software Access:
The GNU-gzip program (gzip.exe) and shareware tar program (tar.exe) are available via Anonymous FTP from the following site: wuarchive.wustl.edu, in the directory, /systems/msdos/gnuish, files: gzip124x.zip and gnutar.zip

15. Data Access

Contact Information:
1) Source Data Contact:
USGS/EDC DAAC
EROS Data Center
Sioux Falls, SD 57090
Phone: (605)594-6091
FAX: (605)594-6963
Email: edc@eos.nasa.gov
2) Data Preparation Contact:
Peter Schlesinger / Dan Nepstad / Paul Lefebvre
Woods Hole Research Center
PO Box 296, 149 Woods Hole Rd.
Woods Hole, MA 02543
Phone: (508)540-9900
Fax: (508)540-9700
Email: pschles@whrc.org
Data Center Identification:
Not Applicable
Procedures for Obtaining Data:
Not Available
Data Center Status/Plans:
Not Applicable

16. Output Products and Availability

Not Applicable

17. References

ACKNOWLEDGMENT: The base data used for this subset were part of the preliminary release of the Global Land Cover Characteristics Database (GLCC) program distributed by the EROS Data Center Distributed Active Archive Center (EDC DAAC), located at the U.S. Geological Survey's EROS Data Center in Sioux Falls, South Dakota. The base data used for that data set were comprised of the International Geosphere Biosphere Programme (IGBP) 1-km AVHRR 10-day composites for April 1992 through March 1993 (Eidenshink and Faundeen, 1994).

The information in this metadata was largely extracted from the documents describing the preliminary release of the GLCC database at USGS/EDC, see: GLCC Database http://edcwww.cr.usgs.gov/landdaac/glcc/globdoc.html, first made available on Decmber 13, 1996.

Other References Used in this Metadata:

Eastman, J.R., 1997. IDRISI for Windows Version 2.0. Clark Labs for Cartographic Technology and Geographic Analysis, Clark University, Worcester, MA

Eidenshink, J.C. and Faundeen, J.L., 1994, The 1 km AVHRR Global Land Data Set: First Stages in Implementation. International Journal of Remote Sensing 15(17): 3,443-3,462.

USGS Generic Metadata for AVHRR, AVHRR Metadata http://edcwww.cr.usgs.gov/nsdi/html/avhrr/avhrr
Zhu, Z., and Yang, L., 1996. Characteristics of the North America 1-km AVHRR Data Set. International Journal of Remote Sensing.

For more information see:

Moody, A., and Strahler, A.H., 1994, Characteristics of Composited AVHRR Data and Problems in their Classification. International Journal of Remote Sensing, 15(17):3,473-3,491.

18. Glossary of Terms

Not Available

19. List of Acronyms

Acronym Definition
ASCII American Standard Code for Information Interchange
AVHRR Advanced Very High Resolution Radiometer
DAAC Distributed Active Archive Center
EDC EROS Data Center
GLCC Global Land Cover Characterization
GNU GNU's not UNIX
IGBP International Geosphere Biosphere Programme
LBA Large Biosphere-Atmosphere experiment
NASA National Aeronautics and Space Administration
NDVI Normalized Difference Vegetation Index
NOAA National Oceanographic and Atmospheric Administration
POES Polar Orbiting Earth Satellite
RMS Root Mean Square

20. Document Information

Document Revision Date:
October 26, 2004
Document Review Date:
Not Available
Document ID:
(currently leave this blank)
Citation:
(currently leave this blank)
Document Curator:
Not Available
Document URL:
http://whrc.org/LBA_data/Amaz_1K_NDVI.htm