20010301: Nexrad Level III radar composites

On Thu, 1 Mar 2001, Mike Leuthold wrote:

> That is where I fall down since I'm using McIDAS to generate all my
> composites.  Not much good in Gempak.  The AREA files are somehow munged
> in the process and won't display the intensity bar.  

Mike, 
You might need to follow the way CIMSS included their information since that is
the format I followed for adding the scaling for those products on the color
bar.


> > 
> > If you have thought about what features are needed in the program which
> > mosaics the radars, I'd be interested in talking to you.
> 
> A couple of things...
>       I am using both precip and clear air mode.  Many times, the RADAR
> isn't switched over to precip right away.  However doing both, one sees
> all kinds of crap, like chaff for example.  Also, some RADAR's (one
> mainly-IWA) don't run their ground clutter removal routines and that mucks
> things up.  I't would be nice to try to remove those test pattern scans
> too, but I have no idea how to do that.  Also, I do checking for RADARs
> that haven't sent data for awhile and make sure I don't use that data.

Mike,

I do precip and clear mode to- storing the binned dbz rather than the 0-15
category. Then, whe stations overlap, I take the maximum value. That handles
the switch from clear air to precip.

Now for the clutter junk, first, I can cut off most of it by adjusting the
FINT minimum value- generally to 0 dBZ for filled contours. I can also plot
the entire grid cell filled with the value instead of contouring- which would
allow more clutter to show- the contouring generally smooths out the clutter.
Of course you could apply the sm5s() function, or selectively  plot using
the sgt() or mask() functions. This is one benifit of having the gempak
gfunc routines available. I have used the relative maximun routine
in gfunc to identify areas of "interesting weather" to select
possible floater sites, or the higher res regions.

Anyhow, did Tom Y. help with the AREA display question you had?
I think McIDAS munbers the row/columns from top down which is
backwards from GEMPAK (generally bottom up). If this is your problem,
then depending on how you calculate the row offset, you could see the McIDAS
display 1 row displaced from GEMPAK if you don't account for the 0 vs 1 based
problem, or you are plotting at the bottom of the pixel location instead of
the midpoint.

Chiz


> 
> Mike
> 
> 
> > 
> > Steve Chiswell
> > Unidata User Support
> > 
> 
> --
> Mike Leuthold
> Atmospheric Sciences/Institute of Atmospheric Physics
> University of Arizona
> address@hidden
> 520-621-2863
> 
> 
>