SMEX02 Landsat Thematic Mapper Imagery, Iowa

Summary

This data set provides imagery from Landsat 5 Thematic Mapper (TM) and Landsat 7 Enhanced Thematic Mapper (ETM+) data for use in studying land cover features during the Soil Moisture Experiment 2002 (SMEX02). The images are the result of combining bands 4, 3, and 2 as red, green, and blue to generate false-color composites. This study was conducted during June and July 2002 in the area of Ames, Iowa, USA. One false-color image is provided for each day. Data are provided in Georeferenced Tagged Image File Format (GeoTIFF) files and TIFF world files (TFW), 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

Jackson, T. J. and M.H. Cosh. 2003. SMEX02 Landsat Thematic Mapper Imagery, Iowa. Boulder, CO, USA: National Snow and Ice Data Center. Digital media.

Overview Table

Category	Description
Data format	GeoTIFF imagery (.tif) and TIFF world files (.tfw).
Spatial coverage and resolution	41.7°N to 42.7°N, 93.8°W to 93.2°W.
Temporal coverage	Data were available over five days from 6 June 2002 to 17 July 2002.
Tools for accessing data	Open these files in an appropriate image processing or image viewing application.
File naming convention	MMDDYY.TIF and MMDDYY.TFW where MM is the month, DD is the day and YY is the year (after 2000).
File size	Files are approximately 20 MB each.
Parameter(s)	The data are false-color images that can be used to identify land cover and vegetation.
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) Name and Title

Thomas J. Jackson, Hydrologist, and Michael H. Cosh, General Physical Scientist, USDA ARS Hydrology Lab.

Technical Contact

Acknowledgements

Many graduate students and volunteers collected the field data. The investigators would like to thank the Soil Moisture Experiment 2002 Science Team and the National Soil Tilth Laboratory 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-E, Terrestrial Hydrology, and Global Water Cycle Programs.

2. Detailed Data Description

For this study, TM and ETM+ bands 4, 3, and 2 were combined to make false-color composites. This band combination makes vegetation appear as shades of red. Brighter reds indicate thicker vegetation. Soils with little or no vegetation appear as shades from white (sands) to green or brown, depending on moisture and vegetation content. Blue indicates water. Urban areas appear as blue-gray. Clouds and snow appear bright white.

Format

Data are provided as GeoTIFF image files with associated .TFW files containing georeferencing information. GeoTIFF defines a set of publicly available TIFF tags that describe cartographic and geodetic information associated with TIFF images. GeoTIFF enables referencing a raster image to a known geodetic model or map projection. The initial tags are followed by image data, that in turn, may be interrupted by more descriptive tags. By using the GeoTIFF format, both metadata and image data can be encoded into the same file.

TFW files provide georeference information for the image with the same file name. Each TFW file is a text file with six numbers, described below:

1st row: the dimension of a pixel in map units in the x direction
2nd row: rotation term for row (0)
3rd row: rotation term for column (0)
4th row: the dimension of a pixel in map units in the y direction
5th row: x coordinate for upper left corner
6th row: y coordinate for upper left corner

File Naming Convention

All file names use the following convention:
MMDDYY.TIF and MMDDYY.TFW.
MM = month, DD = day, and YY = year (after 2000).

File Size

File sizes are approximately 20 MB each.

Spatial Coverage

Southernmost Latitude: 41.7°N
Northernmost Latitude: 42.7°N
Westernmost Longitude: 93.8°W
Easternmost Longitude: 93.2°W

Spatial Resolution

The Landsat TM and ETM+ data are high-resolution (30 m) data.

Projection

Universal Transverse Mercator (UTM) Zone 15.

Temporal Coverage

Data were available over five days from 6 June 2002 to 17 July 2002.

Parameter or Variable

Parameter Description

The data are false-color images that can be used to identify land cover and vegetation.

Parameter Source

TM scenes from Landsat 5 and ETM+ scenes from Landsat 7 were acquired during the study period. The following table details the Landsat coverage for the dates of the study.

Date	Landsat number	Path
June 6	7	27
June 23	5	26
July 1	7	26
July 8	7	27
July 17	7	26

Sample Data Record

The following image is a screen shot of a portion of the image file "060602.tif."

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

Total volume is approximately 100 MB.

Software and Tools

Open these files in an appropriate image processing or image viewing application.

Related Data Collections

See Soil Moisture Experiment (SMEX) for more information.

4. Data Acquisition and Processing

Sensor or Instrument Description

TM is a multispectral scanning radiometer carried on Landsats 4 and 5. The TM has seven spectral bands, with a spatial resolution of 30 m for most bands.

ETM+, an improved version of TM, is carried on Landsat 7. The ETM+ has eight spectral bands with a spatial resolution of 30 m for most bands.

5. References and Related Publications

U.S. Geological Survey (USGS). Landsat Missions. 1 May 2008. http://landsat.usgs.gov/ 1 May 2008.

Sheffner, Ed. Landsat Program. 5 October 1991. http://geo.arc.nasa.gov/sge/landsat/landsat.html 31 October 2007.

6. Document Information

Acronyms and Abbreviations

The following acronyms and abbreviations are used in this document.

AMSR-E	Advanced Microwave Scanning Radiometer - Earth Observing System
ETM+	Enhanced Thematic Mapper Plus
FTP	File Transfer Protocol
GEOTIFF	Georeferenced Tagged Image File Format
SMEX	Soil Moisture Experiment
TFW	TIFF World File
TM	Thematic Mapper
UTM	Universal Transverse Mercator

Document Creation Date

November 2003

Document URL

http://nsidc.org/data/docs/daac/nsidc0199_smex_landsat_tm.gd.html