A tandem pair of Advanced Land Imager (ALI) and Landsat Enhanced Thematic Mapper Plus (ETM+) scenes covering the same part of Kruger National Park (KNP), South Africa (including the Skukuza tower site and rest camp), were acquired about a minute apart on May 30, 2001. The ALI is one of three instruments aboard NASA's first New Millennium Program Earth Observing 1 (EO-1) satellite. ALI is a technology validation testbed that employs novel wide-angle optics and a highly integrated multispectral and panchromatic spectroradiometer.
The tandem pair was produced to evaluate the differences between ALI and ETM+ and determine if technology similar to that of the ALI is suitable for future land imaging that will continue the observations begun by the Landsat satellites in 1972.
The ALI and ETM+ images are false color composites combining shortwave infrared (1.65 µm), near infrared (.79 µm), and visible (.57 µm) wavelengths, displayed as red, green, and blue, respectively. Dense vegetation appears green. The similarity of the images demonstrates the ability of the ALI to produce data comparable to ETM+. Several SAFARI 2000 field campaigns conducted in KNP provided ground-based data needed to evaluate measurements from each of the satellite sensors.
Each band is stored as an individual binary file. A metadata file accompanies each set of ALI and ETM+ band files to document the path and row number, sample and line counts, band file names, and the sun azimuth and elevation angles. There is also a calibration parameter file that was used for 1R processing.
Cite this data set as follows:
Irish, R. A. 2005. SAFARI 2000 ALI/ETM+ Tandem Image Pair for Skukuza, South Africa, May 2001. Data set. Available on-line [http://daac.ornl.gov/] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/821.
Each band is stored as an individual binary file. There are no header records or embedded tags. The image files contain only image data. An ASCII metadata file accompanies each set of ALI and ETM+ band files and can be identified by the MTP designator in the file name. The metadata files document the path and row number, sample and line counts, band file names, and the sun azimuth and elevation angles. The Landsat-7 data set also includes the calibration parameter file that was used for 1R processing and can be identified by the L7CPF designator in the file name.
The ALI data values are stored as 16 bit (big endian) scaled radiances and the ETM+ data values are stored as 8-bit scaled radiances. The equations used to convert the scaled digital numbers to radiance units are given in the companion file.
A summary of ALI and ETM+ instrument characteristics is provided below:
0.4 - 2.4 µm
0.4 - 2.4 µm*
Pan Band Resolution
Number of Bands
* excluding the thermal band (10.4 - 12.5 µm)
The spectral bands for ALI as compared to ETM+ is provided below:
0.433 - 0.453
0.45 - 0.515
0.45 - 0.52
0.525 - 0.605
0.53 - 0.61
0.63 - 0.69
0.63 - 0.69
0.775 - 0.805
0.78 - 0.90
0.845 - 0.89
1.20 - 1.30
1.55 - 1.75
1.55 - 1.75
2.08 - 2.35
2.09 - 2.33
0.48 - 0.69
0.52 - 0.90
Additional information about the ALI instrument, data format, and data processing is found in the companion file: ftp://daac.ornl.gov/data/safari2k/remote_sensing/ali_etm_tandem/comp/ALI_ETM_pair_readme.pdf.