SMEX03 Landsat Thematic Mapper NDVI and NDWI: Oklahoma

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 10 July 2003 were used to create large-scale maps of the NDVI and NDWI for both northern and southern Oklahoma, USA regional study areas in order to accurately estimate the surface soil moisture via microwave remote sensing. Data are in flat, eight-bit 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.

Jackson, Thomas J., and Mike H Cosh. 2007. SMEX03 Landsat Thematic Mapper NDVI and NDWI: Oklahoma. Boulder, Colorado USA: National Snow and Ice Data Center. Digital media.

Overview Table

Category	Description
Data format	Flat binary data files in 8-bit format (little-endian) Oklahoma North image: 2800 by 1840 Oklahoma South image: 3600 by 1920
Spatial coverage and resolution	Southernmost Latitude: 34.49° N Northernmost Latitude: 35.39° N Westernmost Longitude: 98.29° W Easternmost Longitude: 97.76° W 30 m resolution
Temporal coverage and resolution	10 July 2003 Measurements were made one time for this regional study area.
Tools for accessing data	ArcView, ENVI, or other similar software package.
File naming convention	mmddyy_ss_iiii.bin
File size	4.9 - 6.6 MB per 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)

Thomas J. Jackson
Michael H. Cosh
USDA ARS Hydrology/Remote Sensing Laboratory
Bldg. 007, Rm. 104, BARC-West
Beltsville, MD 20705 USA

Technical Contact

Acknowledgements

The investigators would like to acknowledge the numerous graduate students and volunteers who collected the field data, in addition to the SMEX03 Science Team and Grazinglands Research Laboratory for their assistance. The investigators would also like to thank 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, 8-bit little-endian binary data files. Data were scaled in order to maximize the dynamic range. Users must apply Equations 1 and 2 to convert the Digital Number (DN) to NDVI and NDWI values:

NDVI	=	DN/255	(Equation 1)
NDWI	=	DN/255-0.5	(Equation 2)

The dimensions of the Oklahoma North image are 2800 rows by 1840 columns, and the dimensions of the Oklahoma South image are 3600 rows by 1920 columns.

File and Directory Structure

Data are on the FTP site in the NDWI_NDVI directory. Four binary files are contained within this directory, as described in Table 1.

Table 1. Files Contained in this Data Set

File Name	Description	File Size
071003_ON_NDVI.bin	Contains NDVI data for the Oklahoma North regional study area for 10 July 2003.	5032 KB
071003_ON_NDWI.bin	Contains NDWI data for the Oklahoma North regional study area for 10 July 2003.	5032 KB
071003_OS_NDVI.bin	Contains NDVI data for the Oklahoma South regional study area for 10 July 2003.	6750 KB
071003_OS_NDWI.bin	Contains NDWI data for the Oklahoma South regional study area for 10 July 2003.	6750 KB

 

File Naming Convention

Files are named according to the following convention and as described in Table 2:

mmddyy_ss_iiii.bin

where:

Table 2. Description of File Name Variables

Variable	Description
mm	two-digit month
dd	two-digit day
yy	two-digit year
ss	Site (OS = Oklahoma South; ON = Oklahoma North)
iiii	Index (NDVI, NDWI)
.bin	Indicates that this is a binary data file.

Example: 071003_ON_NDVI.bin

File Size

File sizes range from 4.9 to 6.6 MB.

Spatial Coverage

The data set covers Oklahoma North and South regional study areas:

Southernmost Latitude: 34.49° N
Northernmost Latitude: 35.39° N
Westernmost Longitude: 98.29° W
Easternmost Longitude: 97.76° 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
Oklahoma North	Northing	Easting	Latitude	Longitude
Upper Left Corner	4081020 N	585790 E	36.87122	-98.037441719
Upper Right Corner	4081020 N	640990 E	36.86460	-97.418273713
Lower Left Corner	3997020 N	585790 E	36.11405	-98.046766559
Lower Right Corner	3997020 N	640990 E	36.10761	-97.433591947
Oklahoma South
Upper Left Corner	3920100 N	560380 E	35.42248	-98.334881531
Upper Right Corner	3920100 N	617980 E	35.41732	-97.700496383
Lower Left Corner	3812100 N	560380 E	34.44865	-98.342696988
Lower Right Corner	3812100 N	617980 E	34.44367	-97.715762369

Spatial Resolution

All four Landsat NDVI and NDWI data files cover an area with interior dimensions of 30 m by 30 m.

Projection

The projection is Universal Transverse Mercator (UTM), Zone 14 with World Geodetic System 1984 (WGS 84) ellipsoid International Terrestrial Reference Frame (ITRF) and Conventional Terrestrial Reference System (CTRS) realization. Projection is in meters.

Temporal Coverage

Data were acquired on 10 July 2003, which is assumed to be a reasonable approximation for the study period.

Parameter or Variable

Parameter Description

The parameters of this data set are NDVI and NDWI. NDVI is the difference between the visible red and near-infrared 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 divides the difference between the mid-infrared and near-infrared bands by the sum of those two bands, thereby giving a measurement of soil moisture. Refer to Equations 3 and 4.

Parameter Range

In general, the NDVI and NDWI vary between -1 and +1. For this data set, however, the parameter range is 0 to 1 for the NDVI and -0.5 to 0.5 for the NDWI; refer to Equations 1 and 2. Missing values are set to 0.

Parameter Source:

Two TM scenes from Landsat 5 were used to produce this NDVI and NDWI data set. The path rows are a composite of 28/25 and 28/36.

Sample Data Images

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

Figure 1. Oklahoma North NDVI 10 July 2003 Sample Image		Figure 2. Oklahoma South NDWI 10 July 2003 Sample Image

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

The total data volume is approximately 23 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.

Data Source

Data were derived from bands 3 (red), 4 (near-infrared), and 5 (mid-infrared) of the Landsat 5 TM sensor.

Derivation Techniques and Algorithms

NDVI and NDWI calculation

The NDVI and NDWI were computed for each pixel using the following equations (Gao, 1996):

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

and

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

5. References and Related Publications

Please refer to 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 4 lists acronyms used in this document:

Table 4. Acronyms

Acronym	Description
AMSR-E	Advanced Microwave Scanning Radiometer - Earth Observing System
CTRS	Conventional Terrestrial Reference System
DN	Digital Number
ENVI	Environment for Visualizing Images
FTP	File Transfer Protocol
ITRF	International Terrestrial Reference Frame
NASA	National Aeronautics and Space Administration
NDVI	Normalized Difference Vegetation Index
NDWI	Normalized Difference Water Index
NSIDC	National Snow and Ice Data Center
ON	Oklahoma North
OS	Oklahoma South
SMEX	Soil Moisture Experiment
TM	Thematic Mapper
URL	Uniform Resource Locator
UTM	Universal Transverse Mercator
WGS 84	World Geodetic System 1984

Document Creation Date

February 2008

Document URL

http://nsidc.org/data/docs/daac/nsidc0332_smex03_srs_ndvi_ndwi_ok.gd.html