New tool for calculating GLIMS gains for ASTER

[Bruce Raup]

Hi all,

I just made my ASTER gain tool web-accessible.  By going to

http://glims.colorado.edu/~braup/aster_gain.html

you can get the optimal ASTER gains for a snowy target as a function of 
day-of year, latitude, and band.  Note that this is optimized for snowy 
targets, as an accumulation area.

The output takes some getting used to.  An example:

ASTER gains:
Key:  1: high  2: norm  3: low1  4: low2  5: bright  6: dark
For DOY=314, Lat=-82, Band=1:  Gain =   1.573312  (high gain at 57.33% 
saturation)

The calculated "gain" is 1.57....  The integer portion indicates the gain 
level, according to the Key, and the fractional portion indicates the 
degree of saturation at that gain level.


Advanced users:

The CGI program uses the "GET" method (the parameters are encoded in the 
URL), so you can access the tool by script.  See the example shell script 
below.

Best wishes to all for the holidays and the New Year.
Bruce


Example script

#!/bin/sh

outfile=aster_gains.txt
rm -f $outfile
lat='-82'
for doy in 314 44 ; do
  for band in 1 2 3 ; do
    wget --output-document=- "http://glims.colorado.edu/cgi-bin/aster_gain.pl?doy=$doy&lat=$lat&band=$band" >> $outfile
  done
done
# End of script


Output:

ASTER gains:
Key:  1: high  2: norm  3: low1  4: low2  5: bright  6: dark
For DOY=314, Lat=-82, Band=1:  Gain =   1.573312  (high gain at 57.33% saturation)
ASTER gains:
Key:  1: high  2: norm  3: low1  4: low2  5: bright  6: dark
For DOY=314, Lat=-82, Band=2:  Gain =   1.427165  (high gain at 42.72% saturation)
ASTER gains:
Key:  1: high  2: norm  3: low1  4: low2  5: bright  6: dark
For DOY=314, Lat=-82, Band=3:  Gain =   1.425849  (high gain at 42.58% saturation)
ASTER gains:
Key:  1: high  2: norm  3: low1  4: low2  5: bright  6: dark
For DOY=44, Lat=-82, Band=1:  Gain =   1.357891  (high gain at 35.79% saturation)
ASTER gains:
Key:  1: high  2: norm  3: low1  4: low2  5: bright  6: dark
For DOY=44, Lat=-82, Band=2:  Gain =   1.266658  (high gain at 26.67% saturation)
ASTER gains:
Key:  1: high  2: norm  3: low1  4: low2  5: bright  6: dark
For DOY=44, Lat=-82, Band=3:  Gain =   1.265837  (high gain at 26.58% saturation)

-- 
Bruce Raup
National Snow and Ice Data Center
University of Colorado
449 UCB,  Boulder, CO 80309
Phone:  303-492-8814
http://cires.colorado.edu/~braup/