NOAA-NESDIS
Regional And Mesoscale Meteorology Team
Daily Satellite Discussion
Wednesday October 29,1997
Figure 1
GOES-9 10.7 um IR Average Radiance
click to enlarge
Figure 2
GOES-9 10.7 um IR Minimum Radiance
click to enlarge
Today's images are a preview of products currently under development for future use at AWIPS sites. The first figure is an averaged radiance image produced from GOES-9, 10.7 micrometer channel over the western half of the US. It was constructed by taking the radiance values at 1800 UTC at a given pixel location from September 13-30, 1997, and averaging. This average image shows several features: Cloudiness in the Pacific Northwest and Rocky Mountain regions, and land surface features due to clear skies over California, Arizona, and other areas of the southwest. While very useful, this kind of image may not show a single major event, which can be averaged out. Such events may show up in other types of statistics, such as the minimum radiance(coldest temperature) image in the second figure.

The minimum radiance image (figure 2) was produced from the same data set and procedure as the above averaged radiance image, except that the minimum value was determined. This type of image can highlight single events with the coldest cloud top temperatures during the period. Cold cloud tops(blues and greens) over the Pacific northwest can be seen, matching the evidence from the averaged image. However, cloudiness over the Pacific and Arizona is not present in the average image. This is due to two hurricanes entering this region, and impacting the minimum image. Edges of the dissipating Hurricane Linda can be seen over the Pacific in the lower left. The blue/green cloud tops of Hurricane Nora can be seen over the Arizona - Mexico border. Thus, the minimum image can be used to determine single major events during a given month, while average images tend to show more persistent features.

Cindy Combs

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

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