NOAA-NESDIS
Regional And Mesoscale Meteorology Team
Satellite Discussion
Monday May 18, 1998
Today's picture of the day shows the smoke resulting from fires burning in Mexico and Central America. On Monday, May 11, the smoke was transported with the flow ahead of a mid-latitude cold front across the Gulf of Mexico into the Atlantic. In this Visible loop of GOES-8 images, the smoke is advected at the low and mid-levels, across the Gulf, over South Florida and into the Atlantic Ocean and Caribbean Sea. Figure 1, below shows the smoke two days earlier where it has gathered in the Gulf of Mexico, impacting the Gulf Coast states. Figure 2 is a Goes-8 reflectivity product image, derived by subtracting the longwave IR channel 4 scene temperature from that of 3.9 micrometer channel 2, and scaling the result. The fires stand out as white spots, due to the high response to changes in scene temperature of the 3.9 micrometer channel, compared to the 10.7 micron channel.

Figure 1 Figure 2
GOES-8 Visible, May 9, 1998 click to enlarge GOES-8 Reflectivity Product, May 9, 1998 click to enlarge
Figures 3 and 4 below are AVHRR LAC (Advanced Very High Resolution Radiometer Local Area Coverage) images of an area S.E. of Mexico City. See Figure 5 for areal coverage of the AVHRR images. The LAC passes are infrequent but offer 1 km. IR imagery over the fires. The Visible image is 1 km. and matches the reflectivity image in coverage. The white dots represent fires in the reflectivity but caution must be used in making this distinction. GOES-8 imagery, with its 15 minute or better frequency, can be used to ascertain where the fires are located by the longevity of the bright spot. Highly reflective clouds and noise can be eliminated in this way. In this loop of Reflectivity product images, the recurrent bright yellow signatures represent hotter or wider spread fires. The reappearing bright white to light grey signatures are also more than likely fires. The matching Visible loop shows the huge smoke plumes in animation. By viewing the high resolution AVHRR with the Goes-8 loop sequences, one can get a good depiction of the ongoing fire situation.

Carol Vaughn
Figure 3 Figure 4
NOAA-14 1 km. AVHRR LAC Visible, May 14, 1998 click to enlarge NOAA-14 1 km. AVHRR LAC Reflectivity Product, May 14, 1998 click to enlarge

Back to top
Figure 5
AVHRR Coverage (click to enlarge)

We welcome your comments and discussion at :
ramsdis@comet.ucar.edu


Previous RAMMT Satellite Discussions