Fires in Montana

September 12th, 2006 |

GOES-11/12/13 shortwave IR
A large (208,000 acre) wildfire continued to burn near Derby Mountain in southwestern Montana on 12 September. A QuickTime animation of the 3.9 micrometer shortwave IR imagery from GOES-11, GOES-12, and GOES-13 (above) shows the “hot spots” associated with this fire — on the grayscale enhancement applied to these images, the warmest temperatures are black, and the coldest temperatures are white. However, note that some GOES-12 pixels in the vicinity of the fire are white, indicating a cold pixel; there is a problem with the 3.9 micrometer detectors on GOES-12, and pixel values that should be very hot “roll over” and are actually indicated as cold temperatures. This same problem was noted on GOES-11 during the post-launch evaluation of that satellite a few years ago, but there was no GOES-11 pixel roll-over noted for these particular hot fires (and fortunately, the recently-launched GOES-13 has not yet exhibited this behavior). Because of this hot spot detection discrepancy, the GOES-12 Wildfire ABBA flagged this fire as a “saturated” pixel (yellow), while the GOES-11 Wildfire ABBA flagged it as a “processed fire” (red pixel).

An AWIPS 4-panel comparison of MODIS vs. GOES shortwave IR and visible channels (below) show that this fire also saturated the MODIS Band 20 detector (as indicated by the “NO DATA” cursor value); the visible images also reveal that a smoke plume was drifting east-southeastward from the fire source (which was very apparent on this MODIS true color image).
MODIS/GOES-12 shortwave IR, visible

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