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[Staging #CCM-472749]: Re: 20150522: TDWR Level III data from NOAA NEXRAD Operational Support Facility in McX and McV

Hi Barry,

re:
> Would you have time to take a look at a TDWR Level III reflectivity file
> that isn't working in McX or McV and let us know if you find what needs
> to be done to make it work in those packages? (I also checked IDV 5.1u2,
> and it doesn't work there, either.)
> 
> I ask because we have two users in CIMSS - one a McX user and the other
> a McV user - who want to use the reflectivity and velocity data from
> their data source but only the velocity data is working in McX and McV.
> 
> I attached the two files they provided (reflectivity data in
> TDEN_SDUS00_TR0DEN_201405202229 and velocity data in
> TDEN_SDUS00_TV0DEN_201405202229).

I verified that I too can display the TV0 file in McIDAS-X but not the
TR0 image.

re:
> Here's a summary of what I found while investigating the issue:
> 
> * Bob Rabin (the McX user) is receiving their TDWR Level 3 velocity
>   and reflectivity files from the NOAA NEXRAD Operational Support
>   Facility (hereafter NNOSF).

Question:

- how does one go about getting images from the NNOFS?

re:
> * I confirmed that he and Joleen Feltz (the McV user) are correct -
>   the velocity files work in McV, McX and IDV, while the reflectivity
>   ones do not work in any of those packages.

I confirmed this finding also.

re:
> * I requested that Kevin Baggett give me a raw real-time TDWR Level 3
>   reflectivity file from our McXCD server (getting its TDWR data from
>   NOAAPORT) so I could test it. He provided one and I found that it
>   works in all three packages (McV, McX, IDV).

We use the NOAAPort TDWR images routinely in GEMPAK, McIDAS-X and TDS,
so we would know if there was something wrong.

re:
> * Bob Carp downloaded sample TDWR Level 3 reflectivity, velocity and
>   other products from NCDC and reported that they work fine in McV.

OK, good test.

re:
> I had previously asked Bob Rabin and Joleen if getting their data from
> NCDC (instead of NNOSF) is an option since that works in McV (we
> haven't checked it in McX).

I have not recently downloaded any Level 3 products from NCDC, but I have
done so in the past, and I never had any problems with any of their products.

> Bob Rabin replied:
> "/The time resolution of the TDWR data we need are unavailable from
>  NCDC (for the case we are analysing). The data were converted to
>  TDWR Level-III format from TDWR native format at the [NNOSF]. I
>  suspect there is an error in the format of the Level-III
>  reflectivity files they produced (since they are not recognized in
>  McIDAS-X or V)/."

Hmm...  Do you know anything more about the "time resolution" that Bob
is talking about, or can we ask Bob to more fully describe what he
means?

The error I see in the TR0 file that you sent is that the divider
short (2 byte) value at the beginning of the product description block
is not what it should be according to the NEXRAD, -1 (minus one).
I tried munging the code to ignore this, but the values read after this
look like garbage which suggests that the problem is sometime before
this, like in the product message header.

re:
> * So, in summary, we know that:
> o TDWR Level 3 reflectivity files from the *NOAAPORT**data stream*
>   work fine in McV, McX and IDV

Yup, and in GEMPAK.

> o the ones from *NNOSF* do not work in any of them (McV, McX and IDV)

I can verify that the TR0 file you sent me does not work in Unidata
McIDAS-X.  I will check with our GEMPAK person to see if it works
in GEMPAK.

> o the ones from *NCDC* work fine in at least McV (we haven't
>   checked them in IDV or McX) - but that's probably irrelevant
>   since BobR said that NCDC doesn't offer the time resolution of
>   the TDWR data that they need

Again, I would really like to know more about the time resolution issue.
The ICD for NEXRAD Level III products indicates a time resolution down
to the second, and the code in nexrutil.c expects the time resolution
down to the second.

re:
> * BobR and Joleen said that NNOSF will try to fix the reflectivity
> data format, if we can help them figure out what's wrong with the files

OK, good.  I will try to figure out exactly where the TR0 file
deviates from the ICD.  This may take a bit of digging on my part.

re:
> I think that covers all the relevant points, though I've included all
> the emails below if you'd like to see them.

OK, thanks.  I will keep digging to see if I can figure out what exactly
is amiss and let you know.

Cheers,

Tom
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Ticket Details
===================
Ticket ID: CCM-472749
Department: Support McIDAS
Priority: Normal
Status: Open