The Greek island of Elafonisos in the Pelaponessus region suffered from major wildfires in August 2019.
By Jose Prieto (EUMETSAT)
The animation (Figure 2) shows the evolution of the fires' intensity in the course of 10 August in Elafonisos island (Greece) as seen by Meteosat-11 channel 3.9 µm. The red hotspot shows that the fires on the island were the most intense around 07 UTC (Figure 1, top right, click to expand), 11, 15 and 17 UTC, and were almost extinguished by the end of the animation.
Figure 2: Meteosat-11 channel 3.9µm animation, 10 August 06:00–20:45 UTC
This channel is sensitive to high temperatures in a fraction of a pixel and in this case the corresponding brightness temperature competed in the same hues (and values) with hot dry areas, which reflect solar radiation under the clear skies that day (large red 'patches' across the area shown). Alternatively displaying the temperature difference 3.9–10.8 µm further enhances the differentiation of fires from the hot land areas (Figure 3).
As a sole predictor, that difference is a better sign of fire in the absence of cloud. Channel 4 confuses fire and hot pixels. The difference, however, confuses fires with cloud during the day. Most fire algorithms rely on both variables to determine the presence of fire in the pixel.
Unfortunately, the following day the fires reignited, due to strong winds in the area. On the animation in Figure 3 the bright red pixels show that they were very intense around 08:00–09:00 UTC.
Figure 4: Meteosat-11 channel 3.9µm animation, 11 August 06:00–13:00 UTC
MODIS on the Terra satellite captured one of the most intense moments of the burning, at 10:30 UTC on 10 August, as a long uniform plume propagating in a south-westerly direction (Figure 4). However, the fire anomalies product did not spot it as such.
One orbit later (12:10 UTC) the corrected reflectance product from MODIS, with fire and thermal anomalies superimposed, shows Italy appearing to be plagued by fires (red dots), in particular Sicily and the Algerian coast (Figure 5). Red dots are not confirmed fires, but generally anomalies.
Tourists Evacuated on Greek Island as Wildfire Rages Nearby (Time)
Major fires on Greek island (Severe Weather EU/Twitter)
Previous case studies
Devastating wildfires near Athens (23 July 2018)