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20010617: Station Plot w/ RADAR overlay

>From: Daryl Herzmann <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200106180311.f5I3B2p02935

>Hello,
>       I have been sucessful at creating a surface plot with RADAR
>overlay.  An example plot can be seen here
>http://www.meteor.iastate.edu/mesonet/data/20radarOverlay_0.gif
>
>       My question is how can I build logic in my plotting script to
>ignore overlaying the radar when the radar is in clear air mode?   I
>suppose that a hack would be to count the number of files in the past 20
>minutes and make an assumption based on that.  I would like a more elegant
>way, if one exists.
>
>TIA,
>       Daryl
>

Daryl,

Assuming you are plotting the N0R data for the base reflectivity:

If the radar is in Precip mode, then you will also see fields of
N0S and NVL. When the radar is in clear air mode, you wont have fields
for storm relative winds and vertically integrated liquid.

So, in the script, you could use a logic that determines the N0R file,
and if the N0S or NVL file also exists for that time you can assume
precip mode.

One downfall is that during the winter, many sites stay in clear air mode
when it is snowing, and you may want to see that.

Of course, the GEMPAK code can read the actual data files and determine
which mode the radar is operating in, so it would be possible to create a 
small program using the im_simg routine to return a 1/0 exit status
that would identify the radar mode. You would still have the problem
that I mention above regarding winter conditions.

Steve Chiswell
Unidata User Support