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Dataset Documentation:
Amazon Basin Subset of the 8 km x 8 km Resolution Global Pathfinder Advanced Very
High Resolution (AVHRR) Land FTP Data
Summary:
This data set, a subset of that produced as part of the NOAA/NASA Pathfinder
AVHRR Land (PAL) program, contains the Northern half of the South American
continent in a 10-day composite of Normalized Difference Vegetation Index
(NDVI) at 8 km resolution. The data, derived from the Advanced Very High
Resolution Radiometers (AVHRR) on the "afternoon" NOAA operational
meteorological satellites (NOAA-7, -9, -11), cover the period from 1982 to
1992. The Pathfinder Program produces long-term ata sets processed in a
consistent manner for global change research.
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 the 8 km x 8 km Resolution Global Pathfinder
Advanced Very High Resolution (AVHRR) Land FTP Data
Data Set Introduction:
This data set, a subset of that produced as part of the NOAA/NASA
Pathfinder AVHRR Land (PAL) program, contains the northern portion
of the South American continent in a monthly composite of Normalized
Difference Vegetation Index (NDVI) at 8 km resolution. The data,
derived from the Advanced Very High Resolution Radiometers (AVHRR)
on the "afternoon" NOAA operational meteorological satellites
(NOAA-7, -9,-11), cover the period from 1982 to 1992. The Pathfinder
Program produces long-term data sets processed in a consistent
manner for global change research.
Objective/Purpose:
Not Available
Summary of Parameters:
The Normalized Difference Vegetation Index (NDVI) is derived from
the visible and near-infrared channel reflectances (0.58 to 0.68 um
and 0.73 to 1.10 um, respectively)
Discussion:
Not Available
Related Data Sets:
Not Available
2. Investigator(s):
Investigator(s) Name and Title:
Mary James; Peter Schlesinger, M.A., Daniel Nepstad, Ph.D., Paul
Lefebvre, M.S.
Title of Investigation:
Source Data Title:
Pathfinder AVHRR Land Data
Data Preparation Title:
Land-use in Amazonia and the Cerrado of Brazil: State of
Knowledge and GIS Database
Contact Information:
1) Source Data Investigator:
Ms. Mary James
Goddard Global Change Data Center
EOS Distributed Active Archive Center(DAAC)
Code 902.2
NASA Goddard Space Flight Center
Greenbelt, Maryland 20771
Phone: 301-614-5224
Fax: 301-614-5268
Email: daacuso@daac.gsfc.nasa.gov
2) Data Preparation Investigators:
Peter Schlesinger / Dan Nepstad / Paul Lefebvre
The 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:
Spectral Wavelengths
On the NOAA-7, NOAA-9, and NOAA-11 satellites, the AVHRR sensor
measures emitted and reflected radiation in five channels (bands) of
the electromagnetic spectrum: a visible (0.58 to 0.68 micrometer)
band that is used for daytime cloud and surface mapping; a
near-infrared (0.725 to 1.1 micrometer) band used for surface water
delineation and vegetation cover mapping; a mid-infrared (3.55 to
3.93 micrometer) band used for sea surface temperature and nighttime
cloud mapping; a thermal infrared (10.5 to 11.5 micrometer) band
used for surface temperature and day and night cloud mapping; and
another thermal infrared (11.5 to 12.5 micrometer) band used for
surface temperature mapping (Kidwell 1991).
Vegetation Index
The first AVHRR channel is in a part of the spectrum where
chlorophyll causes considerable absorption of incoming radiation,
and the second channel is in a spectral region where spongy
mesophyll leaf structure leads to considerable reflectance. This
contrast between responses of the two bands can be shown by a ratio
transform; i.e., dividing one band by the other. Several ratio
transforms have been proposed for studying different land surfaces
(Tucker, 1979). The Normalized Difference Vegetation Index (NDVI) is
one such ratio, which has been shown to be highly correlated with
vegetation parameters such as green-leaf biomass and green-leaf area
and, hence, is of considerable value for vegetation discrimination
(Justice et al. 1985).
NDVI Relationships With Geophysical Variables
A ratio between bands is of considerable use in reducing variations
caused by surface topography (Holben and Justice 1981). It
compensates for variations in radiance as a function of Sun
elevation for different parts of an image. The ratios do not
eliminate additive effects caused by atmospheric attenuation, but
the basis for the NDVI and vegetation relationship holds generally.
The soil background contributes a reflected signal apart from the
vegetation, and interacts with the overlying vegetation through
multiple scattering of radiant energy. Huete (1988) found the NDVI
to be as sensitive to soil darkening (moisture and soil type) as to
plant density over partially vegetated areas.
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:
The source data for these subsets were acquired by Anonymous FTP from the
site: daac.gsfc.nasa.gov, in the directory /data/avhrr/global_8km/
6. Observations:
Data Notes:
Not Available
Field Notes:
Not Available
7. Data Description:
Spatial Characteristics:
Spatial Coverage:
min. X : -9047548.000
max. X : -3879806.250
min. Y : -2224256.500
max.Y : 1408162.375
Spatial Coverage Map:
Not Available
Spatial Resolution:
8 km x 8 km
Projection:
Goode Interrupted Homolosine Projection
Grid Description:
646 columns by 454 rows
Temporal Characteristics:
Temporal Coverage:
January 1982 to December 1992
Temporal Coverage Map:
Not Available
Temporal Resolution:
10-day and monthly composites
Data Characteristics:
Parameter/Variable:
The NDVI in this subset are scaled to an 8-bit unsigned
byte value in the range of 3 to 253. An offset of 128 must
be applied via a gain of 0.008 to derive the original ndvi
value within the range of -1 to +1. For example, to solve
for the ndvi value of the binned 8-bit value of 100, the
following equation is used:
NDVI=((100*0.008) - (128*0.008)) or -0.224.
Variable Description/Definition:
Not Available
Unit of Measurement:
Unitless
Data Source:
The original data were collected by the Advanced Very High
Resolution Radiometer (AVHRR) flown on the NOAA-series
satellites. The data for this subset were downloaded via
WWW from the URL ftp://daac.gsfc.nasa.gov/data/avhrr.
A detailed, comprehensive description of the NOAA
series satellites, the AVHRR instrument, and the AVHRR GAC
1B data can be found in the NOAA Polar Orbiter Data User's
Guide (Kidwell 1991), which can be obtained from NOAA's
National Environmental Satellite Data and Information
Service (NESDIS).
Data Range:
0-253
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 158 granules of this dataset consists of a
single tarred and GNU-gzipped file. Each of the tarred and
GNU-gzipped files in this dataset contains a single flat binary
raster image file and an ASCII documentation file.
Data Format:
Each of the flat binary raster image files in this dataset consists
of 454 rows by 646 columns, comprising 293,284 bytes (8-bit
unsigned). 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.
There are three fill values in each image: 0 is Missing Data
Over Land, 1 is Ocean, 2 is Goode's Interrupted Space. Orientation
is North to South.
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
from the source data using the IDRISI for Windows
geographic analysis system (Eastman, 1997) to include only
the columns 1371-2016 and rows 908-1361 [where the
column/row coordinate of the upper left is (0,0)].
Processing Changes:
Not Applicable
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:
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:
Not Available
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:
EOS Distributed Active Archive Center(DAAC)
Code 902.2
NASA Goddard Space Flight Center
Greenbelt, Maryland 20771
Phone: 301-614-5224
Fax: 301-614-5268
Email: daacuso@daac.gsfc.nasa.gov
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 Available
Data Center Status/Plans:
Not Available
16. Output Products and Availability:
Not Applicable
17. References:
The material for this set of metadata were adapted largely and portions
copied directly from the on-line document at World Wide Web address:
http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/FTP_SITE/readmes/pal.html
The production and distribution of this data set are funded by NASA's
Mission to Planet Earth program. The data are not copyrighted; however, we
request that, when you publish data or results using these data, please
acknowledge as follows:
The authors wish to thank the Distributed Active Archive Center
(Code 902.2) at the Goddard Space Flight Center, Greenbelt, MD, 20771, for
producing the data in their present form and distributing them. The original
data products were produced under the NOAA/NASA Pathfinder program, by a
processing team headed by Ms. Mary James of the Goddard Global Change Data
Center; and the science algorithms were established by the AVHRR Land Science
Working Group, chaired by Dr. John Townshend of the University of Maryland.
Goddard's contributions to these activities were sponsored by NASA's Mission
to Planet Earth program.
The original data set from which this subset is derived is part of
the Pathfinder Land data set archived at the Goddard DAAC. It is derived from
the PAL 8 km Daily data. The Daily data are derived from the NOAA AVHRR
Global Area Coverage (GAC) 1B data, available from NOAA's Satellite Active
Archive.
Metadata References:
Brown, O.W., J.W. Brown, and R.H. Evans. 1985. Calibration of
Advanced Very High Resolution Radiometer observations. Journal of
Geophysical Research, 90:11667- 11677.
Eastman, J.R., 1997. IDRISI for Windows Version 2.0. Clark Labs for
Cartographic Technology and Geographic Analysis, Clark University,
Worcester, MA
Gordon, H.R., J.W. Brown, and R.H. Evans. 1988. Exact Rayleigh
scattering calculations for use with the Nimbus- 7 coastal zone
color scanner. Applied Optics, 27:2111-2122.
Holben, B.N., and C.O. Justice. 1981. An examination of spectral
band ratioing to reduce the topographic effect on remotely sensed
data, International Journal of Remote Sensing, 2:115-133.
Huete, A.R. 1988. A soil adjusted vegetation index (SAVI), Remote
Sensing of the Environment, 25:295-309.
Justice, C.O., J.R.G. Townshend, B.N. Holben, and C.J. Tucker.
1985. Analysis of the phenology of global vegetation using
meteorological satellite data, International Journal of Remote
Sensing, 6:1271-1318.
Kidwell, K. 1991. NOAA Polar Orbiter Data User's Guide. NCDC/SDSD.
National Climatic Data Center, Washington, DC.
McPeters, R.D., et al. 1993. Nimbus-7 Total Ozone Mapping
Spectrometer (TOMS) Data Products User's Guide. NASA Reference
Publication 1323.
NGDC. 1993. 5 Minute Gridded World Elevation. NGDC Data,
Announcement DA 93-MGG-01. Boulder.
Rao, C.R.N. 1993a. Nonlinearity corrections for the thermal
infrared channels of the Advanced Very High Resolution Radiometer:
assessment and recommendations. NOAA Technical Report NESDIS-69.
NOAA/NESDIS. Washington, DC.
Rao, C.R.N. 1993b. Degradation of the visible and near-infrared
channels of the Advanced Very High Resolution Radiometer on the
NOAAP9 spacecraft: assessment and recommendations for corrections.
NOAA Technical Report NESDIS- 70. NOAA/NESDIS. Washington, DC.
Staylor, W.F. 1990. Degradation rates of the AVHRR visible channel
from the NOAA-6, -7, and -9 spacecraft. Journal of Atmospheric and
Oceanic Technology, 7:411-423.
Tucker, C.J. 1979. Red and photographic infrared linear
combinations for monitoring vegetation. Remote Sensing of the
Environment, 8:127-150.
Weinreb, M.P., G. Hamilton, S. Brown, and R.J. Koczor. 1990.
Nonlinearity corrections in calibration of Advanced Very High
Resolution Radiometer infrared channels. Journal of Geophysical
Research, 95:381-7388.
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 Distribute Active Archive Center
EOS Earth Observing System
FTP File Transfer Protocol
GAC Global Area Coverage
GNU GNU's not UNIX
NASA National Aeronautics and Space Administration
NDVI Normalized Difference Vegetation Index
NESDIS National Environmental Satellite Data and Information Service
NOAA National Oceanic and Atmospheric Administration
PAL Pathfinder AVHRR Land program
RMS Root Mean Square
20. Document Information:
Document Revision Date:
September 5, 1997
Document Review Date:
Not Available
Document ID:
(currently leave this blank)
Citation:
(currently leave this blank)
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
(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: James, Mary
Email: daacuso@daac.gsfc.nasa.gov
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 8 km x 8 km Resolution Global Pathfinder Advanced Very High Resolution (AVHRR) Land FTP Data
Activity: WHRC Tropical Forest Ecology Datasets for Amazonia and the Cerrado
Project: PAL (NOAA/NASA Pathfinder AVHRR Land Program)
Site_Information:
Site:
Amazon Basin
Region:
Amazon Basin
Westernmost_Longitude: -90
Easternmost_Longitude: -38
Northernmost_Latitude: 14
Southernmost_Latitude: -22
Time_Period:
Temporal_Coverage:
Start_Date: 19820101
End_Date: 19921231
Temporal_Resolution:
Weekly
Parameter_Description:
Topic: Biosphere
Term: Vegetation
Parameter: Vegetation Index
Sensor: AVHRR (Advanced Very High Resolution Radiometer)
Source: NOAA-11
Parameter_Description:
Topic: Biosphere
Term: Vegetation
Parameter: Vegetation Index
Sensor: AVHRR (Advanced Very High Resolution Radiometer)
Source: NOAA-7
Parameter_Description:
Topic: Biosphere
Term: Vegetation
Parameter: Vegetation Index
Sensor: AVHRR (Advanced Very High Resolution Radiometer)
Source: NOAA-9
Keywords:
Amazon
Brazil
GIS
Global Change
Human Impacts
LBA
Land Use/Land Cover Change (LU/LCC)
NDVI
Pathfinder AVHRR Land (PAL) Program
South America
Tropical Forests
Woods Hole Research Center (WHRC)
Description:
This data set, a subset of that produced as part of the NOAA/NASA Pathfinder AVHRR Land (PAL) program, contains the Northern half of the South American continent in a 10-day composite of Normalized Difference Vegetation Index (NDVI) at 8 km resolution. The data, derived from the Advanced Very High Resolution Radiometers (AVHRR) on the "afternoon" NOAA operational meteorological satellites (NOAA-7, -9, -11), cover the period from 1982 to 1992. The Pathfinder Program produces long-term data sets processed in a consistent manner for global change research.
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 NOAA/NASA Pathfinder AVHRR Land program, GSFC DAAC, Greenbelt, MD.
Data_Set_Link:
URL: ftp://ftp.whrc.org/Pre-LBA/pathf8vi/
Label: Pathfinder AVHRR data directory
Data_Set_Link:
URL: http://www.whrc.org/science/tropfor/LBA/WHRCpathftmp.htm
Label: Pathfinder AVHRR data set documentation online at WHRC