Like GOES-East, of the six instruments on GOES-West used for observing the Earth and Sun, it is the "Advanced Baseline Imager" (ABI) instrument that provides visible and infrared views the earth. The ABI produces images at 16 different wavelengths (called bands and/or channels).
Note: During post-launch testing of GOES-West, an issue with a cooling system was discovered. The loop heat pipe subsystem, which transfers heat from the ABI electronics to the radiator for cooling, is not operating at its designed capacity.
The consequence of this is inadequate cooling for some of the infrared (IR) channels on the instrument during parts of the night, leading to partial loss of ABI imagery.
During nighttime hours, for part of the year, the sun shines onto the ABI detectors, which heat up faster than they can be cooled. The detectors become warmer than they're designed to operate, and as a result, emissions from the Earth overwhelm some infrared channels, meaning a useful signal is not available.
The individual channels are as follows:
Visible Bands
There are two visible bands, blue and red, named relative to their location on the visible portion of the electromagnetic spectrum.
While in their natural state, these images would appear in blue and red hues respectively, but colors have been desaturated to appear in grayscale. Since these are "visible" channels, the images will appear black at night.
Near-Infrared Bands
Channel 3: The "Veggie" band
The centralized wavelength for this band is 0.86 µm (micrometers).
Although this is a "near-infrared" band (not visible to the eye), vegetation is readily seen at this wavelength, giving it the nickname "veggie" band. It is useful in assessing land characteristics when determining fire and flood potential. For example, forest fire damage will appear darker than nearby unaffected areas, which helps pinpoint locations where significant rainfall may lead to flooding and mudslides.
Water is very absorptive of this wavelength, which makes it appear dark in the image, resulting in a high contrast between land and water.
Water Vapor Bands
The satellites do not directly detect moisture but instead detect temperature. Water vapor absorbs radiation at these particular frequencies, and thus the satellite does not sense much radiation when there is high water vapor. It records this as a low temperature, which is interpreted as high water vapor content. When radiation is not absorbed and thus received by the satellite, it senses a high temperature and consequently interprets a low amount of water vapor.
As a result, the depth at which the satellite peers into the atmosphere will vary with the amount of moisture over any particular point from day to day.
Channel 8: The "Upper-Level" Water Vapor band
The centralized wavelength for this band is 6.2 µm (micrometers).
The primary use for this band is the detection of upper level atmospheric features such as jet streams, troughs/ridges, and signs of potential turbulence.
The centralized wavelength for this band is 9.6 µm (micrometers).
This band provides information about the dynamics of the atmosphere near the tropopause (the atmospheric boundary between the troposphere below – where we live – and the stratosphere above). The ozone band on the ABI does not give exact information on total ozone; rather, multiple ABI IR bands are used to calculate an estimate. The Total Ozone product provides information to forecasters that helps them forecast areas of atmospheric turbulence and provide better forecasts of air quality.
This image is not a single channel but a combination of several GOES-R channels along with a polar orbiting satellite. During daytime, bands 1, 2 and 3 (red, blue and "veggie") are combined to produce an approximation of how it would appear if viewed with human eyes from space.
At night, bands 7 and 13 are combined and colorized. The nighttime blue colors represent liquid water clouds such as fog and stratus, while gray to white indicate higher ice clouds. Finally, from a polar orbiting NASA satellite, the nighttime city lights are added.
