Winds and Cloud Heights (Vaughn, Campbell)
A program which calculates geometric cloud heights from shadows is nearly
ready for general distribution to RAMSDIS sites. The program requires
human input, so is most useful for special case studies.
An asynchronous stereo/wind analysis program is under continuing development.
In this quarter, a mixture of GOES and AVHRR data was used to derive heights
matching the GOES 8 plus GOES 9 results. Also, favorable comparisons
have been made with the NESDIS automatic cloud motion analysis. The
program is still in the demonstration phase. Analysis with
4 km, channel 4 data seems to be working, since its results match very
well with the VIS 1 km data analysis. Next we need to test the combination
of GOES 4 km IR and AVHRR 4 km IR data (GAC). The following two figures
are of interest (Click on images for full-size imagery):
Figure 1. GOES 9 visible image with cloud heights and winds derived
using AVHRR LAC data. GOES data were available at 20:45, 21:00, 21:30
and AVHRR at 21:20. The numbers represent the height of the clouds
or land in hectometers (98 = 9.8 km). The height of the ground should
be subtracted from the analyzed height.
Figure 2. GOES 9 IR image with cloud heights/winds derived with
the use of AVHRR LAC data. The 1 km LAC data were remapped into the
GOES 4 km IR data file. After adjusting for the analyzed height of
the ground, cloud heights match results from the 1 km visible analysis
to within 0.5 km.
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For the stereo analysis a REMAP program is required. The McIDAS
REMAP program has been modified to allow 2-byte output and may be of general
interest to the McIDAS community.