The Tatlawiksuk Fire, 41 miles south of McGrath, has been burning steadily (as of posting) since June 4th, sparked by the recent lightning storms in Southwest Alaska last week. These VIIRS animations of DayLandCloudFire (left) and the i04 band (right) show the change of the fire perimeter (in bright red) from June 8th to June 9th.
DayLandCloudFire RGB with Active Fire Points overlay
i04 band – (3.74 um) with Active Fire Points overlay
In the DayLandCloudFire RGB and i04 (3.74um) above, notice the grey pixel in the southern extension of the fire perimeter. This is where the sensor became saturated on that pixel, which is in the hottest part of the fire. Essentially, it was so hot in that part of the fire that it “saturated” the sensor, so the pixel looks cooler (in this colormap grey indicates cooler brightness temperatures than green, yellow, or red). (Think of it as an overload error). However, even though there doesn’t appear to be a fire in that grey pixel, there is. The m13 / 4.0 um image (below) reports the hottest brightness temperature in that area is approximately 179 degrees Celsius, so we know there is a fire in that location. The only problem is that VIIRS m-bands, like the m-13, are lower resolution, 750 m rather than 375 m.
m13 band – (4.0 um)
m13 band – (4.0 um) with fire heat points
i04 band – (3.74 um)
Fire Heat Points