Todays picture of the day will focus on blowing dust in Mexico, just
west of Texas. This
occurred on Wednesday April 15 1998 at 2100Z. The visible image is
shown in Figure1. In this figure, there is little if any indication
of blowing dust. The same holds true for Channel 2 at the same time
(Figure 2).
| Figure 1 |
Figure 2 |
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GOES-9 channel 1, 4-15-98, 2100Z
click to enlarge
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GOES-9 channel 2, 4-15-98, 2100Z
click to enlarge
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Upon careful examination of channel 4, one can see a few east-west bands
that were slightly brighter than their surroundings (Figure 3). The
contrast in this channel was not large enough to make this feature
easily detectable. Figure 4 shows the channel 4 minus channel 5
difference product. In this derived product, the region of blowing
dust showed sufficient contrast to make it easily detectable as darker
regions. That
this was blowing dust and not smoke from a fire was determined by the
lack of a bright spot in channel 2 (Figure 2).
| Figure 3 |
Figure 4 |
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GOES-9 channel 4, 4-15-98, 2100Z
click to enlarge
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GOES-9 4-5 difference, 4-15-98, 2100Z
click to enlarge
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