SMEX03 Landsat Thematic Mapper NDVI and NDWI: Georgia

Summary

This Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) data set was developed from Landsat 5 Thematic Mapper (TM) data for use in studying land cover features during the Soil Moisture Experiment 2003 (SMEX03).Data acquired on 20 July 2003 were used to create large-scale maps of the NDVI and NDWI for both northern and southern Georgia, USA regional study areas in order to accurately estimate the surface soil moisture via microwave remote sensing. These data are uncorrected for the atmosphere and should not be compared to long term data records of vegetation. Data are in flat, four-byte binary format and are available via FTP.

These data were collected as part of a validation study for the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E). AMSR-E is a mission instrument launched aboard NASA's Aqua Satellite on 04 May 2002. AMSR-E validation studies linked to SMEX are designed to evaluate the accuracy of AMSR-E soil moisture data. Specific validation objectives include assessing and refining soil moisture algorithm performance; verifying soil moisture estimation accuracy; investigating the effects of vegetation, surface temperature, topography, and soil texture on soil moisture accuracy; and determining the regions that are useful for AMSR-E soil moisture measurements.

Citing These Data

The following example shows how to cite the use of this data set in a publication. For more information, see our Use and Copyright Web page.

Bosch, David D. and Michael H. Cosh. 2008. SMEX03 Landsat Thematic Mapper NDVI and NDWI: Georgia. Boulder, Colorado USA: National Snow and Ice Data Center. Digital media.

Overview Table

Category	Description
Data format	Flat binary data files in 4-byte format (little-endian) 3440 rows by 1840 columns
Spatial coverage and resolution	Southernmost Latitude: 30.96° N Northernmost Latitude: 31.90° N Westernmost Longitude: 83.97° W Easternmost Longitude: 83.36° W 30 m resolution
Temporal coverage and resolution	20 July 2003
Tools for accessing data	ArcView, ENVI, or other similar software package
File naming convention	mmddyy_ss_iiii.fst
File size	24.7 MB per binary file 1 KB per header file
Parameter(s)	NDVI NDWI
Procedures for obtaining data	Data are available via FTP.

Table of Contents

1. Contacts and Acknowledgments
2. Detailed Data Description
3. Data Access and Tools
4. Data Acquisition and Processing
5. References and Related Publications
6. Document Information

1. Contacts and Acknowledgments

Investigator(s)

David D. Bosh
Southeast Watershed Research Laboratory (SEWRL)
US Department of Agriculture (USDA) - Agricultural Research Service (ARS)
Tifton, GA 31794 USA

Michael H. Cosh
US Department of Agriculture (USDA) - Agricultural Research Service (ARS)
Hydrology and Remote Sensing Laboratory
Beltsville, MD 20705 USA

Technical Contact

Acknowledgements

The investigators would like to acknowledge the numerous graduate students and volunteers who collected the field data, the Soil Moisture Experiment 2003 Science Team, and the Southeast Watershed Research Laboratory (SEWRL) for their assistance. They also thank the National Aeronautics and Space Administration (NASA) for their generous contributions to the study. This work was supported by the NASA Aqua AMSR, Terrestrial Hydrology, and Global Water Cycle programs.

2. Detailed Data Description

Format

Data are presented in flat binary data files composed of 4-byte floating point numbers in little-endian ordering with accompanying ENVI ASCII header files. Image dimensions are 3440 rows by 1840 columns.

File and Directory Structure

Data are on the FTP site in the NDWI_NDVI directory, as described in Table 1.

Table 1. Files Contained in this Data Set

File Name	Description	File Size
072003_GA_NDVI.fst	Contains NDVI data for the Georgia regional study area for 20 July 2003	24.7 MB
072003_GA_NDVI.hdr	NDVI ENVI header file	1 KB
072003_GA_NDWI.fst	Contains NDWI data for the Georgia regional study area for 20 July 2003	24.7 MB
072003_GA_NDWI.hdr	NDWI ENVI header file	1 KB

 

File Naming Convention

Files are named according to the following convention:

mmddyy_ss_iiii.fst

where:

Table 2. Description of File Name Variables

Variable	Description
mm	Two-digit month
dd	Two-digit day
yy	Two-digit year
ss	Site (GA)
iiii	Index (NDVI, NDWI)
.fst	Indicates that this is a dbFast binary data file
.hdr	Indicates that this is a header file

Example: 072003_GA_NDVI.fst

File Size

Binary files are 24.7 MB each and header files are 1 KB each.

Spatial Coverage

This data set covers the Georgia regional study area as referenced by the following:

Southernmost Latitude: 30.96° N
Northernmost Latitude: 31.90° N
Westernmost Longitude: 83.97° W
Easternmost Longitude: 83.36° W

A detailed geographic description of the data set is shown in Table 3. Geolocation coordinates correspond to the center of each corner pixel.

 

Table 3. Geolocation of the Images

Regional Study Area	Image Coordinates
Georgia NDVI & NDWI	Northing	Easting	Latitude	Longitude
Upper Left Corner	3532170	219030	31.890693508	-83.970521377
Upper Right Corner	3532170	274200	31.902987034	-83.387729205
Lower Left Corner	3429000	219030	30.961072002	-83.941333124
Lower Right Corner	3429000	274200	30.972927502	-83.364252777

Spatial Resolution

Both Landsat NDVI and NDWI data files have a pixel size of 30 m by 30 m.

Projection

The projection is Universal Transverse Mercator (UTM), Zone 17, with the North American Datum 1983 (NAD 83) applied.

Temporal Coverage

Data were acquired on 20 July 2003.

Parameter or Variable

Parameter Description

The parameters are NDVI and NDWI.

NDVI is the difference between the visible red and Near-InfraRed (NIR) bands over their sum. The NDVI is a measure of vegetation amount and condition. It is associated with vegetation canopy characteristics such as biomass, leaf area index, and percentage of vegetation cover. NDVI helps researchers determine the density of vegetation in an area.

NDWI is the difference between the NIR and Mid-InfraRed (MIR) bands over their sum. NDWI gives a measurement of soil moisture. Refer to Equations 1 and 2 in the Data Acquisition and Processing section for NDVI and NDWI algorithms.

Parameter Range

Typically, the NDVI and NDWI vary between -1 and +1. For this data set, however, the parameter range is -0.525532 to 0.764273 for the NDVI and -0.0668948 to 1.01413 for the NDWI. Missing values are set to 0.

Parameter Source

Two TM scenes from Landsat 5 path row 18/38 were used to produce this NDVI and NDWI data set.

Sample Data Image

Figures 1 and 2 show sample thumbnail images from this data set.

Figure 1. Georgia NDVI 20 July 2003. Sample from Image File 072003_GA_NDVI.fst.		Figure 2. Georgia NDWI 20 July 2003. Sample from Image File 072003_GA_NDWI.fst.

3.Data Access and Tools

Data Access

Data are available via FTP.

Volume

The total data volume is approximately 49.4 MB.

Software and Tools

Tools appropriate for viewing these data are ArcView, ENVI, or other similar software package.

Related Data Collections

• AMSR-E Soil Moisture Validation Data: Data sets from SMEX campaigns available at NSIDC.
• AMSR-E/Aqua Data at NSIDC: AMSR-E standard products available at NSIDC.

4. Data Acquisition and Processing

Sensor or Instrument Description

The TM instrument is a multispectral scanning radiometer carried on Landsats 4 and 5. It has seven spectral bands with a spatial resolution of 30 m for most bands. Refer to the TM Web site for additional technical details.

Data Source

Data were derived from bands 3 (red), 4 (NIR), and 5 (MIR) of the Landsat 5 TM sensor.

Derivation Techniques and Algorithms

NDVI and NDWI calculation

The NDVI and NDWI were computed for each pixel using Equations 1 and 2, respectively, as applied to the TM bands described in Table 4 (Gao, 1996):

NDVI =	ρ(band 4) - ρ(band 3)
		(Equation 1)
	ρ(band 4) + ρ(band 3)

and

NDWI =	ρ(band 4) - ρ(band 5)
		(Equation 2)
	ρ(band 4) + ρ(band 5)

where:

Table 4. Algorithm Description

Variable	Description
ρ(band 4)	Reflectance value for the TM NIR band 4
ρ(band 3)	Reflectance value for the TM red band 3
ρ(band 5)	Reflectance value for the TM MIR band 5

Refer to the Parameter or Variable section for a description of NDVI and NDWI.

5. References and Related Publications

Please visit the USDA SMEX 03 Web site for in-depth information on the science mission and goal of the SMEX project.

6. Document Information

Acronyms

Table 5 lists acronyms used in this document.

Table 5. Acronyms

Acronym	Description
AMSR-E	Advanced Microwave Scanning Radiometer - Earth Observing System
ASCII	American Standard Code for Information Interchange
DN	Digital Number
ENVI	Environment for Visualizing Images
FTP	File Transfer Protocol
MIR	Mid-InfraRed
NAD 83	North American Datum 1983
NASA	National Aeronautics and Space Administration
NDVI	Normalized Difference Vegetation Index
NDWI	Normalized Difference Water Index
NIR	Near-InfraRed
NSIDC	National Snow and Ice Data Center
SMEX	Soil Moisture Experiment
TM	Thematic Mapper
URL	Uniform Resource Locator
UTM	Universal Transverse Mercator

 

Document Creation Date

March 2008

Document URL

http://nsidc.org/data/docs/daac/nsidc0330_smex03_srs_ndvi_ndwi_ga.gd.html