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A new way to deal with negative values
http://www.weathergraphics.com/forum/viewtopic.php?f=9&t=696
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Author:  Fred [ Thu Jun 30, 2005 8:14 am ]
Post subject:  A new way to deal with negative values

# TEMPERATURE INVERSION AT 925 MB LEVEL
#
# Plot temp diff between 1000 mb and 925 mb levels
#
ERASE
ANALYZE,STOR=2 TEMP H925 STOR=1 TEMP H000
#
ANALYZE,OVER FILL COLOR=100:255:036 GRTN=0 SDIF=2:1
ANALYZE,OVER FILL COLOR=000:255:255 GRTN=0 SDIF=1:2

ANALYZE,OVER FILL COLOR=216:255:000 GRTN=5 SDIF=2:1
ANALYZE,OVER FILL COLOR=000:209:255 GRTN=5 SDIF=1:2

ANALYZE,OVER FILL COLOR=255:240:000 GRTN=10 SDIF=2:1
ANALYZE,OVER FILL COLOR=000:154:255 GRTN=10 SDIF=1:2

ANALYZE,OVER FILL COLOR=255:204:000 GRTN=15 SDIF=2:1
ANALYZE,OVER FILL COLOR=000:080:255 GRTN=15 SDIF=1:2

ANALYZE,OVER FILL COLOR=255:161:000 GRTN=20 SDIF=2:1
ANALYZE,OVER FILL COLOR=000:045:255 GRTN=20 SDIF=1:2

ANALYZE,OVER FILL COLOR=255:127:000 GRTN=25 SDIF=2:1
ANALYZE,OVER FILL COLOR=022:000:255 GRTN=25 SDIF=1:2

ANALYZE,CONT LINE=1 CINT=5 COLOR=160:000:100 GRTN=0 SDIF=2:1
ANALYZE,CONT LINE=1 CINT=5 COLOR=000:000:160 LSTN=0 SDIF=2:1
STAMP

The above script is primarily given as an example how to deal with negative values in another way. Previous scripts added a constant to the temperature to get a positive value. Here the difference is taken between two values. Depending on the sequence in the SDIF command you always have a positive value. The advantage is that you can ask the real value.

This solution is invented by Les Hamilton, a member of the MT of GEO. GEO is the Group of Earth Observation. The group’s focus is on receiving weather satellites. “Eumetsat's MSG-1, with its spectacular images of Earth every 15 minutes, is an example of the latest satellite being received by the Group's members” (see http://www.geo-web.org.uk/index.html). These images can automatically be used a background in DAWS

The group also publishes a quarterly magazine with lots of attention to DAWS. Previous issues of the GEO Quarterly gave e.g. articles about using Images as background in DAWS, using fleetcode on Meteosat-8 images and getting images from NOAA’s active archive. In the present issue is an introduction to DAWS and in the next will be an extended article about how to make scripts.

As you can see, also for DAWS-users a subscription to GEO is a MUST!

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