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20050512: radar enhancement for composite imagery

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  • Subject: 20050512: radar enhancement for composite imagery
  • Date: 12 May 2005 14:46:46 -0600
Kevin,

The range is -30 to 75 in the composite since both clear air and
precipitation mode are in the same product, whereas the 0 to 75
you refer to is a precipitation mode only.

There are default tables defined in $GEMTBL/sat/imgtyp.tbl 
for the RADAR mosaics, and these will be used when LUTFIL=default.
Always make sure you set LUTFIL in your programs, otherwise you
get any lut that has already been preloaded,

For N0R, the table is upc_rad24.tbl, note the use of 24 colors instead
of 16 for just the reson you state in extending the data range
to both clear air and precip while maintaining the 16 colors used
in the precipitation range of the 0 to 75 dbz nids product.
(Note that -30dbz to 75 dbz is mapped to pixel values of 0 to 105
as used in the imgtype.tbl file.)

Also note, you should specify the GINI image in "SATFIL" and use
PROJ=sat to display the image, since the satellite color partition
defaults to 95 colors, while the radar color partition defaults
to 20 colors (and 20 colors isn't enough for upc_rad24.tbl right?).

In nmap2, you can use the "SAT" image type to select your data set which
is generally $SAT/NEXRCOMP/1km/n0r/n0r_yyyymmdd_hhnn in the
pattern actions I provide (another Gotcha...don't call the directory
"rad" as that will tell nmap2 to use the radar color partition!).

Steve Chiswell
Unidata User Support






On Thu, 2005-05-12 at 14:26, Kevin Polston wrote:
> Hi Steve,
> 
> Hey....I would like to know if there is a enhancement for the composite 
> radar imagery (I believe it is the FNEXRAD).  I am trying to get the 
> luts file I have to be like the osf16_ref.tbl enhancement for the single 
> site radars.  The problem is the composite radar goes from a range of 
> -30 to +75 whereas on the single site radar imagery the data starts at 0 
> and goes to +75.  Is there an enhancement file you have for this or that 
> someone has because I am tired of trying to mess with the file to get it 
> to come out right.  It seems if I make the lower end values look "good" 
> then the higher values (ie, from 40 or 45 on up) are skewed or if I work 
> the higher end then the lower values get skewed.  I have been playing 
> with this for a few weeks now and I was hoping that you or someone would 
> have an enhancement file.  I appreciate your help.  Thanks.
> 
> 
> Kevin Polston
> Senior Instructor, NWSTC
> Kansas City MO 64152
> 
> 816-880-9314 ext 273