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20040427: Level II elevation angles

In 5.7.1, I added the the ability to list the elevation angles in the
level II scan. You will see the following:

1) elevation angles contained in the volume are VCP scan pattern dependent.
   For example, VCP12 contains more scans at lower angles. The ROC pages show
   a sampling of the VCP currently in use at each site, and is weather
   dependent.

2) The sweeps are not necessarily ordered in the volume file by elevation angle,
   so specifying the first sweep in the file is not necessarily the same as N0R.
   The best comparison is by elevation angle as is possible in 5.7.1.

Steve Chiswell
Unidata User Support


On Tue, 27 Apr 2004, Gerry Creager N5JXS wrote:

> What I'm suggesting is that the 0057 L2 data is earlier data than what's
> reported for the 0057 L3 data.
>
> It appears that the data are not occurring at the same time.
>
> Question: Are you looking at Level III N0R and Level II dz with tilt=1,
> or tilt=0.5?
>
> As Steve patiently pointed out to me yesterday, there was a change in
> GPNEXR2 between 5.6 and 5.7.1 where the tilt parameter went from tilt
> levels to tilt elevation angles (or, Steve, that's what I think I
> understood :-)
>
> As I recall tilt=1 would correspond to N1R, in 5.6.m, and tilt=0 :: N0R;
>    in 5.7.1, tilt=0.5 :: N0R, tilt=1.5 :: N1R.
>
> I've just done some real quick looks at my Level III data here: N0R and
> N1R data are not timestamped correctly coming in.  By inspection
> (admittedly not rigorous, the data for DTX show a 5 minute timestamp
> difference (different scans) but the same effective coverage when
> differences in tilt are accommodated.  Admittedly, this could be an
> extremely slow-moving storm, but that's a quick first-impression.  As I
> have more time today I'll look at overlays and better meta-analysis of
> the images, I hope...
>
> gerry
>
> Rob Dale wrote:
> >>Looks to me like there's also a time-shift.  The Level II
> >>data are sent relatively unprocessed, while there's a lot of
> >>radar-site processing and product generation that occurs with
> >>Level III images.
> >
> >
> > But regardless of the amount of time it takes to get from the radarsite to
> > the end user, the 0057Z tilt 1 image should have the echoes in the same spot
> > regardless?
> >
> >  - Rob
>
> --
> Gerry Creager -- address@hidden
> Network Engineering -- AATLT, Texas A&M University
> Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.847.8578
> Page: 979.228.0173
> Office: 903A Eller Bldg, TAMU, College Station, TX 77843
>