Click here to access the original (html) data set document which
you see included below as a text file.
Click here to get to the directory containing the data files
Dataset Documentation:
Amazon Basin Subset of the UNEP/GRID NOAA Global Vegetation Index (GVI)
Summary:
The National Oceanic and Atmospheric Administration / Global Vegetation Index
(NOAA/GVI) archive held by UNEP/GRID is a series of weekly, monthly, seasonal
and annual data files as produced by UNEP/GRID-Geneva from the original
NOAA/GVI data set. The time period covered by these data as held by GRID is
12 April 1982 through 11 September 1994. This subset consists solely of the
weekly variety of those data files for the geographic region of the northern
half of South America.
Table of Contents:
1 Data Set Overview
2 Investigator(s)
3 Theory of Measurements
4 Equipment
5 Data Acquisition Methods
6 Observations
7 Data Description
8 Data Organization
9 Data Manipulations
10 Errors
11 Notes
12 Application of the Data Set
13 Future Modifications and Plans
14 Software
15 Data Access
16 Output Products and Availability
17 References
18 Glossary of Terms
19 List of Acronyms
20 Document Information
1. Data Set Overview:
Data Set Identification:
Amazon Basin Subset of UNEP/GRID NOAA Global Vegetation Index (GVI)
Data Set Introduction:
The National Oceanic and Atmospheric Administration / Global
Vegetation Index (NOAA/GVI) archive held by UNEP/GRID is a series of
weekly, monthly, seasonal and annual data files as produced by
UNEP/GRID-Geneva from the original NOAA/GVI data set. The time
period covered by these data as held by GRID is 12 April 1982
through 11 September 1994.This subset consists solely of the weekly
variety of those data files for the geographic region of the
northern half of South America.
Objective/Purpose:
Not Available
Summary of Parameters:
Global Vegetation Index:
The GVI is derived from NOAA/ Advanced Very High Resolution
Radiometer (AVHRR) Global Area Coverage (GAC) data which are
obtained on a daily basis. For any given week, the highest daily
value of the so-called Normalized Difference Vegetation Index (NDVI)
is sampled to produce a Weekly GVI data file. The NDVI is calculated
from channels one (visible red light) and two (near- infrared light)
values imaged by the AVHRR sensor, as follows: NDVI = (ch. 2 - ch.
1)/(ch. 2 + ch. 1).
Discussion:
Not Available
Related Data Sets:
Not Available
2. Investigator(s):
Investigator(s) Name and Title:
Ronald G. Witt, Regional Coordinator; Peter Schlesinger, M.A.,
Daniel Nepstad, Ph.D., Paul Lefebvre, M.S.
Title of Investigation:
Source Data Title:
NOAA/GVI Weekly Calibrated Vegetation Index
Data Preparation Title:
Land-use in Amazonia and the Cerrado of Brazil: State of
Knowledge and GIS Database
Contact Information:
1) Source Data Investigator:
Ronald G. Witt
UNEP/DEIA/GRID-Geneva
Geneva Executive Centre (GEC) 11
chemin des Anemones CH-1219 Chatelaine
Geneva, Switzerland
Phone:+41-22 979-9029
FAX Phone:+41-22 979-9294/95
Email: rgwitt@gridi.unep.ch
2) Data Preparation Investigators:
Peter Schlesinger / Dan Nepstad / Paul Lefebvre
Woods Hole Research Center
PO Box 296, 13 Church Street
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:
Not Available
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:
Not Available
6. Observations:
Data Notes:
Not Available
Field Notes:
Not Available
7. Data Description:
Spatial Characteristics:
Spatial Coverage:
Location(Decimal Degrees)
Min X -80.9272385
Max X -34.4412079
Min Y -20.0553093
Max Y 12.4446907
Spatial Coverage Map:
Not Available
Spatial Resolution:
The nominal spatial resolution is 16 km at the Equator
Projection:
Plate Carree/Equirectangular
Grid Description:
Rows 226
Columns323
Temporal Characteristics:
Temporal Coverage:
Because of different NOAA satellite and AVHRR sensor
failures, UNEP/GRID-Geneva does not hold all weeks within
the entire 1982-1994 period of time. For example, week 26
of 1993 (June 28 - July 4) is missing, and all related data
files (July, summer, annual) for 1993 were calculated
without taking this week in account. Also, data for year
1994 extend from week 1 to week 36 (January 1-September 11)
only, and thus monthly vegetation index data files are
available for January to August, and the Summer period was
calculated using July, August and weeks 35 and 36
(beginning of September 1994).
Year Week
1982 (Beginning of First Generation product 12 April,
week 15)
1983 Week 26 (27 June - 3 July) ;
Week 31 (1-7 August)
Week 42 (17-23 October)
1984 Week 7 (13-19 February)
Week 8 (20-26 February)
Week 13 (26 March - 1 April)
Week 14 (2-8 April)
Week 49 (3-9 December)
Week 51 (17-23 December)
1985 Week 3 (14-20 January)
Week 5 (28 January - 3 February)
(End of First Generation product 7 April 1985.
Beginning of Second Generation Weekly Composite 9
April 1985.)
1992 Week 11 (9-15 March)
1993 Week 26 (28 June - 4 July)
1994 From 12 September on, weeks > 31are not available
Temporal Coverage Map:
Not Available
Temporal Resolution:
Weekly
Data Characteristics:
Parameter/Variable:
Global Vegetation Index
Variable Description/Definition:
The NDVI is calculated from channels one (visible red
light) and two (near- infrared light) values imaged by the
AVHRR sensor, as follows: NDVI = (ch. 2 - ch. 1)/(ch. 2 +
ch. 1)
Unit of Measurement:
Unitless
Data Source:
Originating Center: UNEP/DEIA/GRID - Geneva
Entry_ID:GNVd0028/104
Data Center: UNEP/DEIA/GRID-GENEVA
> UNEP - Division of Environmental Information and
Assessment - Global Resource Information Database - Geneva
Data Center
URL:http://www.unep.ch
The NOAA/GVI data files held by UNEP/GRID-Geneva cover both
the so-called First Generation and Second Generation NOAA
products.
The original source of these data was:
U.S. National Oceanic and Atmospheric Administration /
National Environmental Satellite Data and Information
Service / National Climate Data Center / Satellite Data
Services Division
Data Range:
0-255
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.
Each of the 635 granules in this dataset consists of a
tarred and GNU-gzipped file (.taz), containing a single flat binary
raster image file and an associated ASCII text file (.doc) both
sharing a common filename.
Data Format:
Each of the flat binary raster image data files in this subset
consists of 323 columns and 226 rows, comprising 72,998 8-bit bytes.
There are no headers, trailers, or delimiters.
The structure of the ASCII 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.
flagdef'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 original data files held by UNEP/GRID-Geneva
have the dimensions of 2500 columns by 904 rows. Each of
the weekly datafiles in this dataset were subset from the
source data using the IDRISI for Windows geographic
analysis system (Eastman, 1997) to include only the columns
687-1009 and rows 660-687 [where the column/row coordinate
of the upper left is (0,0)].
Processing Changes:
Not Applicable
Calculations:
Special Corrections/Adjustments:
Calculated Variables:
Not Available
Graphs and Plots:
Not Available
10. Errors:
Sources of Error:
Not Available
Quality Assessment:
Data Validation by Source:
Not Available
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:
It should be noted that the minimum and maximum values information
reported in each image's associated documentation files is
incorrect. The documentation files in this dataset note values of
0-255, while the actual range of minima and maxima for these data
varies from 0-200.
Any Other Relevant Information about the Study:
Not Available
12. Application of the Data Set:
The NDVI has been correlated with such physical measurements as total
standing biomass, green leaf-area index (LAI) and per cent vegetation cover,
but is probably best described as a relative measure of vegetation vigor and
photosynthetic activity. It is most often used among other applications as a
tool for monitoring temporal changes in vegetation.
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, and
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:
Ronald G. Witt
UNEP/DEIA/GRID-Geneva
Geneva Executive Centre (GEC) 11
chemin des Anemones CH-1219 Chatelaine
Geneva, Switzerland
Phone:+41-22 979-9029
FAX Phone:+41-22 979-9294/95
Email: rgwitt@gridi.unep.ch
2) Data Preparation Contact:
Peter Schlesinger / Dan Nepstad / Paul Lefebvre
Woods Hole Research Center
PO Box 296, 13 Church Street
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 Applicable
Data Center Status/Plans:
Not Applicable
16. Output Products and Availability:
Not Applicable
17. References:
Almost all of the information in this metadata was taken directly from the
UNEP/GRID-Geneva summary document for the original data set, see the World
Wide Web addresses:
http://www.grid.unep.ch/noaagnv28.htm or
http://www.grid.unep.no/gnvd0028.htm
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
The best reference for the data from which this subset is derived is the NOAA
"Global Vegetation Index Users' Guide (rev. Dec. 1994)", compiled and edited
by Katherine B. Kidwell and available from the U.S. Department of Commerce,
NOAA/ NESDIS/NCDC/Satellite Data Services Division, Princeton Executive
Square, Wash. D.C. 20233 USA
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
DEIA Division of Environmental Information and Assessment
GAC Global Area Coverage
GNU GNU's not UNIX
GRID Global Resources Information Database
GVI Global Vegetation Index
NCDC National Climatic Data Center
NDVI Normalized Difference Vegetation Index
NESDIS National Environmental Satellite Data and Information Service
NOAA National Oceanic and Atmospheric Administration
SDSD Satellite Data Services Division
UNEP United Nations Environment Program
20. Document Information:
Document Revision Date:
October 15, 1997
Document Review Date:
Not Available
Document ID:
(currently leave this blank)
Citation:
URL:www.grid.unep.ch/noaagnvi28.txt
Document Curator:
Not Available
Document URL:
(This will be filled in when the guide is ready to be released.)
Return to Pre-LBA page.
Science | Education | Public Affairs | Join The Center | Who's
Who | News
For more information, please write or call us at:
The Woods Hole Research Center
P.O. Box 296
Woods Hole, MA 02543
[WHRC HOME] (508) 540-9900 / Telefax (508) 540-9700or send us email:
info@whrc.org
Problems with this document? Comments? Please send a
message to webmeister@whrc.org
Illustrations by Malcolm Wells - Underground Art Gallery,
Brewster, MA
© The Woods Hole Research Center, 1996. All rights reserved.
Team_Information:
Investigation_Team:
Team_ID: N/A
Investigator:
Name: Witt, Ronald G.
Email: rgwitt@gridi.unep.ch
Investigator:
Name: Schlesinger, Peter
Email: pschles@whrc.org
Investigator:
Name: Nepstad, Daniel C.
Email: dnepstad@whrc.org
Investigator:
Name: Lefebvre, Paul
Email: paul@whrc.org
Contact_Person:
Name: Schlesinger, Peter
Email: pschles@whrc.org
LBA_Science_Component: Land Use and Land Cover
Data_Set_Information:
Data_Set_Title: Amazon Basin Subset of the UNEP/GRID NOAA Global Vegetation Index (GVI)
Activity: WHRC Tropical Forest Ecology Datasets for Amazonia and the Cerrado
Project: LBA (Large-Scale Biosphere-Atmosphere Experiment in the Amazon)
Site_Information:
Site:
Amazon Basin
Region:
Amazon Basin
Westernmost_Longitude: -80
Easternmost_Longitude: -34
Northernmost_Latitude: -12
Southernmost_Latitude: -20
Time_Period:
Temporal_Coverage:
Start_Date: 19820412
End_Date: 19980911
Temporal_Resolution:
Weekly
Parameter_Description:
Topic: Biosphere
Term: Vegetation
Parameter: Vegetation Index
Sensor: AVHRR (Advanced Very High Resolution Radiometer)
Source: NOAA
Keywords:
AVHRR GAC
Amazon
Brazil
GIS
Global Change
Global Vegetation Index (GVI)
Human Impacts
LBA
Land Use/Land Cover Change (LU/LCC)
South America
Tropical Forests
UNEP/GRID
Woods Hole Research Center (WHRC)
Description:
The National Oceanic and Atmospheric Administration / Global Vegetation Index (NOAA/GVI) archive held by UNEP/GRID is a series of weekly, monthly, seasonal and annual data files as produced by UNEP/GRID-Geneva from the original NOAA/GVI data set. The time period covered by these data as held by GRID is 12 April 1982 through 11 September 1994. This subset consists solely of the weekly variety of those data files for the geographic region of the northern half of South America.
Data_Access_Information:
Data_Set_Status: Final
Data_Set_Restrictions: Public
Data_Set_Location: Woods Hole Research Center
Data_Center_Contact: Peter Schlesinger/Dan Nepstad/Paul Lefebvre | pschles@whrc.org
Data_Center_URL: http://www.whrc.org/
Data_Set_Citation:
Produced by the Woods Hole Research Center P.O. Box 296, 13 Church Street, Woods Hole, Massachusetts 02543, from data originally processed at UNEP/Division of Environmental Information and Assessment, Geneva Data Center;
Data_Set_Link:
URL: ftp://ftp.whrc.org/Pre-LBA/grid16vi/
Label: UNEP/GRID NOAA Global Vegetation Index (GVI) data directory
Data_Set_Link:
URL: http://www.whrc.org/science/tropfor/LBA/WHRCgvisum01.htm
Label: GVI data set documentation online at WHRC