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[McIDAS #JBA-785900]: Research Question



Hi Rod,

re:
> Can you tell me the exact commands and steps on how to from our Skype chat:
> 
> a) Find out the time of the scan of the line of the supercell of interest?
>    Using GVARIINFO to get to 2 mins and 50 secs or something like that?

Here is what I sent you previously followed by a step-by-step procedure
that replicates what I told you during our Skype session on Friday:

The GVARINFO command will list the time of a GVAR image as long as the
image is in its original form (meaning that it still contains GVAR
line prefixes). The effective radius images do not have this information
as they are products, but the IR and VIS images you have do. Unfortunately,
GVARINFO does not understand ADDE datasets; it is an old command that
only works with AREA files directly:

HELP GVARINFO
GVARINFO -- Displays information from a GVAR area line
GVARINFO area_number line_number
Parameters:
area_number | area number containing GVAR data
line_number | line number in area coordinates; use T for table of
calibration changes
Keyword:
BUG=201 | Run program in debug mode (def=101)
----------


This can be overcome in a couple of different ways:

- link the original image to an AREA file name

Example:

cd $MCDATA
rm -f AREA2000 AREA2001
ln -s archive/27apr2011/2011117201000i13.c01 AREA2000 <- GVAR VIS image
ln -s archive/27apr2011/goes13.2011.117.201020.BAND_04 AREA2001 <- GVAR IR image

Now, use IMGDISP to display the image centered on the Lat,Lon location
you are interested in:

<from a McIDAS session>

ERASE F
IMGDISP LOC/AREAS.2001 LATLON=34.39 87.85
MAP H

Now move your mouse cursor over the Lat,Lon point of interest
(34.39 87.85) and interrogate the image using IMGPROBE:

-- move cursor to the point in the center of your region of interest
IMGPROBE MODE=N

From the IMGRPOBE listing, get the Line of the image you cursor
is over in File coordinates.  When I just did this, I got a line
number of 384.

Now, run the GVARINFO command to get information about that line:

GVARINFO 2001 384

The operative information from the GVARINFO invocation to me is:

   (GVAR_PFX6.FOR)    SPS time: year        2011 day of year         117 
hh:mm:ss           20:          27:          54 msec         176

Notice that the time of the line is 20:27:54.176.  Compare this
to the nominal time of the image as listed by IMGLIST, 20:25:00.
The difference is two minutes fifty four point 176 seconds.

re:
> b) Find out how the maximum effective radius of ice located at the
>    maximum reflectivity when doing a cross section on McIDAS?

McIDAS does not support analysis of radar volume scans.  I did the
cross section in the IDV using the 20:28:54 NEXRAD Level II volume
scan image that I downloaded from NCDC.

re:
> Can you show a screen-shot too?

I have attached two screen shots.  One shows the vertical cross section
slicing through the 50 dBz isosurface; the other shows the vertical
cross section by itself.

re:
> This is so I can show Bob what results I am getting before sending an
> email.

OK.

Cheers,

Tom
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Ticket Details
===================
Ticket ID: JBA-785900
Department: Support McIDAS
Priority: Normal
Status: Closed

Attachment: RadarVolumeAndVerticalCrossSection_20110427_202854.gif
Description: GIF image

Attachment: RadarVerticalCrossSection_20110427_202854.gif
Description: GIF image


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