VIIRS Day Night Band

This DMSP OLS visible image, taken on a moonless night, shows many city lights in South Carolina, Georgia, Alabama, and portions of Mississippi. But most of Louisiana and Texas are dark, with the exception of the Houston and Dallas Fort Worth areas.

The infrared image shows that the Texan city lights are obscured by thunderstorm cloud cover. They don't appear on the visible image since there is no illumination from moonlight at this time.

Combining the two images into an RGB eliminates the need to interpret the visible and infrared images separately. It clearly shows the thick cloud cover over Texas and western Louisiana, which obscured the cities.

Recall that the DMSP OLS imager has only two channels, visible and longwave infrared. The RGB is made by assigning the visible channel to be red and the infrared channel to be both blue and green. This results in clouds that are cyan and cities that are red. With the new VIIRS imager, we are now able to combine the Day Night Band with potentially 21 other channels, resulting in many new opportunities for multispectral viewing.

To learn more about the VIIRS Day Night Band and its applications, see the COMET module "Advances in Space-Based Nighttime Visible Observation" at https://www.meted.ucar.edu/training_module.php?id=990