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20030326: problem? with RAIN calibration

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  • Subject: 20030326: problem? with RAIN calibration
  • Date: Sat, 29 Mar 2003 15:39:26 -0700
>From: Don Murray <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200303261808.h2QI8OB2008066 McIDAS ADDE RTNEXRAD

Don,

>I'm trying to retrieve data in calibrated units from the
>ADDE servers.  For the most part, the basics are working.
>In answer to my previous question about calibration units,
>these are stored in word 58 (with scale in 59) if AUX=YES
>is included in the ADDE request.

I also updated the IMGLIST lists for FORM=AUX to list out
the mapping between raw and calibrated values.  These mods
are being reviewed at SSEC for the v2003 release, so now is
the time to make modifications if/when needed.  You can
see the effect from the additions by running the following
from McIDAS:

DATALOC ADD RTNEXRAD adde.ucar.edu
IMGLIST RTNEXRAD/N1P ID=FTG FORM=AUX

>I'm running into a problem with the precip products.  If
>I access a 1 hour precip product as brightness, I might
>get a region with some echos showing a region of precip.
>If I use Alt-D to query the value, it shows as 0.00 inches.
>In GEMPAK, this region is shown as > 0.0 on the scale.

This is for a trace amount.  At the time I originally did the
server, I did not want to have to return back non-byte
values for the values.  Later, I realized that this was
needed, but I never went back and addressed the 'trace' precip
amount values.

>If I request the data with calibration of "RAIN" which
>has units of IN and scale of 100, this region of echos
>comes back with values of 0, so they are indistiguishable
>from the no data regions.

They probably should be 0.01 IN (a trace).

>Is it possible to say that this value is 0.01 or some other
>quantifier instead of sending back 0 so that it is distiguishable
>from no data?

I will put this on my list of things to look at in the coming week.

Tom
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