Urban Heat "Islands"

Imagery from the 3.9 um band of the GOES Imager makes it possible to locate urban heat "islands" under clear sky conditions, especially during the night-time hours. As discussed earlier, there is inherent variability

in land-surface temperatures over distances of fractions of a kilometer, even more so around cities and their suburbs. The GOES FOV over cities may be thought of in the same sense as partially filled fields-of-view over fires. This results in higher radiance temperatures being measured at night over cities at 3.9 um than at 10.7 um.

In this example, the signatures of several Midwestern cities can be seen in an image from the early morning of 14 July 1995. The cities are darker (warmer) than their surroundings.

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