NOAA-NESDIS
Regional And Mesoscale Meteorology Team
Daily Satellite Discussion
Thursday July 17, 1997
GOES-8 1 km Remapped Visible (Channel 1)
22:45 UTC
GOES-8 1 km Remapped Visible (Channel 1)
22:45 UTC
Contrast stretched from min/max brightness
(EUVIS command)
Today's pictures of the day focuses on Tropical Storm Danny. Danny, in the Gulf of Mexico, was first designated a Tropical Depression by the Tropical Prediction Center at 2100 UTC yesterday, July 16, 1997, and was upgraded to a Tropical Storm today at 1600 UTC. Air Force Reserve "Hurricane Hunter" C-130 aircraft flew a reconnaissance mission at 1500 ft altitude and located the center at 28:36N 90:43W at 1944 UTC. The extrapolated surface center pressure was 1001 mb, and the maximum flight level winds 49 kt in the SE quadrant of the storm. The 2100 UTC Advisory from the TPC indicated a nearly stationary storm with a very slight drift to the east, and maximum sustained surface winds of 50kt, slightly higher than the 45 kt at 1600 UTC.

The 1st image (upper-left) is an unenhanced visible image with a linear black-white color pallette. The enhancement is very important because the resolution of the GOES visible sensor exceeds the capability of the human eye to perceive different shades of color. With that in mind, let's look at the second image. The brightness range of the image was reduced and the color enhancement (black-white progression) was reduced from 0 to 255. The new range from 32 to 164 now contains the black-white enhancement and allows one to perceive more detail at cloud top.
GOES-8 1 km Remapped Visible (Channel 1)
22:45 UTC
Contrast stretched from min/max cloud brightnesses
GOES-8 4 km IR (Channel 4)
22:45 UTC
Displayed at 1 km and Color Enhanced


The left picture (above) demonstrates an even smaller range of values. Looking at the max and minimum brightnesses in the cloud field, the brightness range from 78 to 162 were used. This provides the most detail in the cloud field. The unremapped IR4 image is also shown for comparison (right).


Ray Zehr/Brian Motta

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

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