Near Infrared Channel - 3.9 microns - Subpixal Response

http://www.meted.ucar.edu/satmet/goeschan/#

• When the Field of View (FOV) is completely filled or completely void of clouds, the 3.9 and 10.7 micron channels may see similar radiance temperatures.  However, when the FOV is partially filled, the 3.9 micron channel always looks warmer since it is less sensitive to sub-pixal views.
• This property is also useful for detecting fires and cities which will look a lot warmer at 3.9 microns than at 10.7 microns.
• A final note on the 3.9 micron channel, at colder temperatures, the data becomes very noisy, like at the tops of high clouds.