Above average temperatures have been persisting over a great portion of the United States, bringing drought-like conditions. One of the areas that have been experiencing the lack in precipitation is the Nantahala National Forest located in Western North Carolina. In Figure 1, the U.S. Drought Monitor shows the severity of the drought, highlighting areas of the Nantahala National Forest under Extreme (red) and Exceptional (purple) drought. More statistics of the drought can be seen and evaluated through the U.S. Drought Monitor website.
Figure 1: The U.S. Drought Monitor of the state of North Carolina and the criteria for drought intensity (right). Currently, one can see that Eastern North Carolina is experiencing no drought, however, Western North Carolina increases in drought intensity, seen by the black circle in the figure.
The extreme drought in Western North Carolina has prompted several wildfires in the Nantahala National Forest. To monitor these wildfires not only during the day but during the night-time hours one can utilize the Near-Constant Contrast (NCC) which is a derived product of the Day/Night Band (DNB) sensor on-board Suomi-NPP, a polar orbiting satellite. The NCC utilizes a sun/moon reflectance model that helps illuminate atmospheric features (i.e., clouds, lightning) and recognizes emitted lights sources (i.e., wildfires and city lights) around the globe.
To infer the current locations of the wildfires in Western North Carolina, an NCC image of a clear-sky atmosphere, during the full moon stage of the lunar cycle is utilized. Figure 2 below highlights a static image of the emitted city lights in Western North Carolina on 17 October 2016 at 0640Z.
Figure 2: NCC image of the emitted city lights located in Western North Carolina on 17 October 2016. In the top-left corner of the figure is the approximate percent visibility of the moon (~full moon) and the corresponding moon elevation angle (in degrees) above the horizon.
Figure 2 will now be compared to Figure 3 (below). Figure 3 consists of the current locations of the wildfires in North Carolina, denoted by the white circles, as of 0710Z on 11 November 2016.
Figure 3: NCC image of the emitted city lights and the wildfires in Western North Carolina on 11 November 2016. In the top-left corner of the figure is the approximate percent visibility of the moon (~full moon) and the corresponding moon elevation angle (in degrees) above the horizon.
An additional tool to complement the NCC is the GOES Infrared (IR) 3.9 um satellite imagery (Figure 4) that can dictate hotspots; areas within the imagery that are very hot, such as wildfires. One can use the same domain, that has been utilized in Figure 2 and 3 and overlay it with the IR imagery. One can see some of the hotspots, expressed in brightness temperature (dark grey to black colors), are located in the same white circles that were seen in Figure 3, verifying the location of the wildfires.
Figure 4: A corresponding GOES IR 3.9 um satellite imagery at 0710Z, 11 November 2016, showing the brightness temperatures (in degrees Celsius) of the hotspots. The same white circles that were used in Figure 3 were overlayed in this figure to complement and verify that the wildfires are located in these specific areas.
For more information on the wildfires click the link, and to see the animation of the fires discussed above, click Figure 5 below.
Figure 5: An animated composite of Figures 2, 3 , and 4, please click on this figure.