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ADDS - Aviation Digital Data Service
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- What do the numbers on the images mean?
The answer depends on the channel so you may want to read the item
below this one for more details on channels. The Visble channel
displays albedo or reflectance expressed as a percentage. For example,
a bright white shade may indicate 70% albedo. The Infrared (IR)
channel is calibrated to temperature and expressed in degrees Celcius.
Where clouds exist, the temperature is that of the tops of clouds.
Where clouds do not exist, the temperature is that of the ground or
the ocean. This information could be very valuable to aviators since
clouds with tops below 0°C, may indicate that an Icing hazard
exists. [An icing hazard could also exist in clouds warmer than
freezing particularly if there is a strong temperature inversion
beneath the cloud.] The Water Vapor channel is also calibrated
to temperature in degrees Celcius. Interpreting the actual values
displayed on the water vapor images is not useful.
- What do the different channels show?
The latest generation of GOES weather satellites (GOES-8,9,10) all
carry 5 imaging sensors. They are in the following portions of the
These web pages provide images from channels 1, 3, and 4 which are
generally the most useful to aviators and meteorologists. More
details in plain English, please. The other 2 channels can be
quite useful to scientists and developers of new products. (An example
where all 5 channels are used in an aircraft icing
application can be found at Research Applications Program of
- Channel 1: Visible (0.6 microns)
- Channel 2: Shortwave Infrared (3.9 microns)
- Channel 3: Water Vapor (.67 microns)
- Channel 4: Infrared (11 microns)
- Channel 5: Infrared (12 microns)