Thematic Mapper
Encyclopedia
One of the Earth observing sensors introduced in the Landsat program
. A Thematic Mapper (TM) was first placed aboard Landsat 4
(decommissioned in 2001), and one is still operational aboard Landsat 5
. TM sensors feature seven bands of image data (three in visible wavelengths, four in infrared) most of which have 30 metre spatial resolution. TM is a whisk broom scanner
which takes multi-spectral image
s across its ground track
.
The Thematic Mapper has become a useful tool in the study of albedo
and its relationship to global warming
and climate change
. The TM on the Landsat 5
has proven useful in determining the amount of ice loss on glaciers due to melting.
Landsat 7
carries an enhanced TM sensor known as the Enhanced Thematic Mapper Plus (ETM+).
Landsat program
The Landsat program is the longest running enterprise for acquisition of satellite imagery of Earth. On July 26, 1972 the Earth Resources Technology Satellite was launched. This was eventually renamed to Landsat. The most recent, Landsat 7, was launched on April 15, 1999. The instruments on the...
. A Thematic Mapper (TM) was first placed aboard Landsat 4
Landsat 4
Landsat 4 is the fourth satellite of the Landsat program. It was launched on July 16th, 1982, with the primary goal of providing a global archive of satellite imagery. Although the Landsat Program is managed by NASA, data from Landsat 4 was collected and distributed by the USGS...
(decommissioned in 2001), and one is still operational aboard Landsat 5
Landsat 5
Landsat 5 is the fifth satellite of the Landsat program. It was launched on March 1, 1984, with the primary goal of providing a global archive of satellite photos. The Landsat Program is managed by USGS, and data from Landsat 5 is collected and distributed from the USGS's Center for Earth Resources...
. TM sensors feature seven bands of image data (three in visible wavelengths, four in infrared) most of which have 30 metre spatial resolution. TM is a whisk broom scanner
Whisk broom scanner
A whisk broom or spotlight sensor is a technology for obtaining satellite images with optical cameras. It is used for passive remote sensing from space. In a whisk broom sensor, a mirror scans across the satellite’s path , reflecting light into a single detector which collects data one pixel at a...
which takes multi-spectral image
Multi-spectral image
A multispectral image is one that captures image data at specific frequencies across the electromagnetic spectrum. The wavelengths may be separated by filters or by the use of instruments that are sensitive to particular wavelengths, including light from frequencies beyond the visible light range,...
s across its ground track
Ground track
A ground track or ground trace is the path on the surface of the Earth directly below an aircraft or satellite. In the case of a satellite, it is the projection of the satellite's orbit onto the surface of the Earth .A satellite ground track may be thought of as a path along the Earth's surface...
.
The Thematic Mapper has become a useful tool in the study of albedo
Albedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...
and its relationship to global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
and climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
. The TM on the Landsat 5
Landsat 5
Landsat 5 is the fifth satellite of the Landsat program. It was launched on March 1, 1984, with the primary goal of providing a global archive of satellite photos. The Landsat Program is managed by USGS, and data from Landsat 5 is collected and distributed from the USGS's Center for Earth Resources...
has proven useful in determining the amount of ice loss on glaciers due to melting.
Landsat 7
Landsat 7
Landsat 7, launched on April 15, 1999, is the latest satellite of the Landsat program. Landsat 7's primary goal is to refresh the global archive of satellite photos, providing up-to-date and cloud-free images. The Landsat Program is managed and operated by the USGS, and data from Landsat 7 is...
carries an enhanced TM sensor known as the Enhanced Thematic Mapper Plus (ETM+).
External links
- NASA's web page on the Thematic Mapper lists sensor specifics.