[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
20030206: NEXRAD calibration information for raw values of zero
This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.
- Subject: 20030206: NEXRAD calibration information for raw values of zero
- Date: Thu, 06 Feb 2003 18:47:08 -0700
>From: Rick Kohrs <address@hidden>
>Organization: SSEC
>Keywords: 200302061458.h16EwY624125 McIDAS nexradir nexraget
Rick,
>Inquiry 11731 says that a raw value of 0 for PRCIPTOT gives a value of
>09997.00.
The 9997 value is a missing data indicator. There are two types of
"zero" values: values that are actually zero, and missing data.
I chose to indicate missing data values in the exact same way that
they are represented in the NEXRAD images themselves.
>I looked at all the different calibrated values for a raw value of 0 and
>all of them give strange results (see attachment).
I don't have time tonight to repeat your extensive examination.
I did, however, check out the base reflectivities at tilts 0 and
1 as a quick check, and get different results:
N0R is the base reflectivity at tilt 0
IMGDISP RTNEXRAD/N0R ID=FTG LINELE= 230 230 PLACE=C MAG= 1 1 EU=BREF SU=X
ALL=11 SF=YES REFRESH='EG GRA=(GRA);MAP FILE=OUTLUSAM MCOL=1 WID=1
GRA=(GRA);BAR (GRA) SU=X X COL=7 ORIENT=VER;TE ?LASTFRM (GRA)'
Image Name ID Day Nominal Time Scan Time Band
---------------- --- ------- ------------ --------- ----
RTNEXRAD/N0R FTG 7 Feb 03038 01:30:00 MISSING 1
File Nominal Image RAW BRIT ECHO VIP
Lat/Lon Line/Element Line/Element DBZ
41:22:34 / 106:15:25 52/ 86 53/ 87 0 0 -9997 0
IMGPROBE: Done
IMGDISP RTNEXRAD/N1R ID=FTG LINELE= 230 230 PLACE=C MAG= 1 1 EU=BREF SU=X
ALL=11 SF=YES REFRESH='EG GRA=(GRA);MAP FILE=OUTLUSAM MCOL=1 WID=1
GRA=(GRA);BAR (GRA) SU=X X COL=7 ORIENT=VER;TE ?LASTFRM (GRA)'
Image Name ID Day Nominal Time Scan Time Band
---------------- --- ------- ------------ --------- ----
RTNEXRAD/N1R FTG 7 Feb 03038 01:30:00 MISSING 1
File Nominal Image RAW BRIT ECHO VIP
Lat/Lon Line/Element Line/Element DBZ
40:28:08 / 105:56:18 153/ 111 154/ 112 0 0 -9997 0
IMGPROBE: Done
In these two cases at least, the output from 'D' is what I intended.
>Also notice that some of the calibrated units are not given a name or a
>unit.
In my two quick tests, I did not see this.
>Tom I think you and Russ wrote this calibration module, so can you shed
>light on my findings?
I wrote the calibration stuff in the NEXRAD server, so Russ is not to
blame if there is a problem :-)
I will make a more systematic investigation along the lines of what you
did and see if I can replicate your results (e.g., lack of units
displayed). I will reiterate, however, that the huge negative values
like -9997 are missing data indicators and need to stay as they are.
Tom
>--------------080504070803020809030006
>Content-Type: text/plain;
> name="Nexrad.out"
>Content-Transfer-Encoding: 7bit
>Content-Disposition: inline;
> filename="Nexrad.out"
>
> NEXRAD/TOPS
> Lat/Lon Line/Element Line/Element K FT
> 29:13:14 / 95:46:44 64/ 40 65/ 41 0 0 243
>
> NEXRAD/SRVEL4
> Lat/Lon Line/Element Line/Element
> 29:25:37 / 95:13:24 234/ 215 235/ 216 0 0 -9997
>
> NEXRAD/SRVEL3
> Lat/Lon Line/Element Line/Element
> 29:24:33 / 95:12:09 236/ 217 237/ 218 0 0 -9997
>
> NEXRAD/SRVEL2
> Lat/Lon Line/Element Line/Element
> 29:22:23 / 95:10:18 240/ 220 241/ 221 0 0 -9997
>
> NEXRAD/SRVEL1
> Lat/Lon Line/Element Line/Element
> 29:28:19 / 95:05:21 229/ 228 230/ 229 0 0 -9997
>
> NEXRAD/PRECIPTOT
> Lat/Lon Line/Element Line/Element IN
> 29:28:19 / 95:05:58 114/ 114 115/ 115 0 09997.00
>
> NEXRAD/PRECIP1
> Lat/Lon Line/Element Line/Element IN
> 29:28:19 / 95:05:58 114/ 114 115/ 115 0 09997.00
>
> NEXRAD/CREF
> Lat/Lon Line/Element Line/Element DBZ
> 29:24:00 / 95:22:03 239/ 203 240/ 204 0 0 -9997
> 0
>
> NEXRAD/BVEL2
> Lat/Lon Line/Element Line/Element
> 29:24:00 / 95:22:03 237/ 201 238/ 202 0 0 -9997
>
> NEXRAD/BVEL1
> Lat/Lon Line/Element Line/Element
> 29:24:00 / 95:22:03 237/ 201 238/ 202 0 0 -9997
>
> NEXRAD/BREF4
> Lat/Lon Line/Element Line/Element DBZ
> 29:24:00 / 95:22:03 237/ 201 238/ 202 0 0 -9997
> 0
>
> NEXRAD/BREF3
> Lat/Lon Line/Element Line/Element DBZ
> 29:24:00 / 95:22:03 237/ 201 238/ 202 0 0 -9997
> 0
>
> NEXRAD/BREF2
> Lat/Lon Line/Element Line/Element DBZ
> 29:24:00 / 95:22:03 237/ 201 238/ 202 0 0 -9997
> 0
>
> NEXRAD/BREF1
> Lat/Lon Line/Element Line/Element DBZ
> 29:24:00 / 95:22:03 237/ 201 238/ 202 0 0 -9997
> 0
>
> NEXRAD/BREF248
> Lat/Lon Line/Element Line/Element DBZ
> 29:19:42 / 95:39:21 237/ 201 238/ 202 0 0 -9997
> 0
>
> NEXRAD/VIL
> Lat/Lon Line/Element Line/Element
> 29:00:17 / 96:03:54 70/ 33 71/ 34 0 0 243
>
>--------------080504070803020809030006--
>
--
+-----------------------------------------------------------------------------+
* Tom Yoksas UCAR Unidata Program *
* (303) 497-8642 (last resort) P.O. Box 3000 *
* address@hidden Boulder, CO 80307 *
* Unidata WWW Service http://www.unidata.ucar.edu/*
+-----------------------------------------------------------------------------+
- Prev by Date: 20030206: McIDAS - Tru64 - ptlist not listing CMAN stations (cont.)
- Next by Date: 20030206: NEXRAD calibration information for raw values of zero (cont.)
- Previous by thread: 20030206: McIDAS - Tru64 - ptlist not listing CMAN stations (cont.)
- Next by thread: 20030206: NEXRAD calibration information for raw values of zero (cont.)
- Index(es):