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[Datastream #TVM-187420]: USPLN feed test and decoder info

Hi again Chris,

re:
> Data format:
> 
> Each 1 minute packet sent has an ASCII header, followed by a record for
> each lightning detection during the past 1 minute.
> 
> Header
> The ASCII header provides information on the creation time of the one
> minute packet and ending date and time of the file.
> 
> Sample Header:
> USPLN-LIGHTNING,2004-10-11T20:45:02,2004-10-11T20:45:02
> Description:
> Name of Product: USPLN-LIGHTNING
> Creation of 1 min Packet (yyyy-mm-ddThh:mm:ss): 2004-10-11T20:45:02
> Ending of 1 min Packet (yyyy-mm-ddThh:mm:ss): 2004-10-11T20:45:02
> 
> NOTE: All times in UTC

I have been looking through data we have received from you and have
some observations and questions:

- The headers we are seeing do not seem to match your description above.
  For instance, consider the following set of data from 18Z today:

  USPLN-LIGHTNING,2006-09-20T18:01:00,2006-09-20T18:01:00
  2006-09-20T17:59:46,30.0591313,-76.0738631,-41.4,1
  2006-09-20T17:59:46,30.050927,-76.0571154,-6.9,1
  ...
  2006-09-20T18:00:36,38.7527522,-112.4778862,0.0,1
  2006-09-20T18:00:36,38.7527488,-112.4778875,0.0,1

  The time on the last flash in the product is 18:00:36, not the
  18:01:00 indicated by the header.  This mismatch seems to be the
  rule, not the exception.  This is not a big deal, but I am curious
  as to why the header is incorrect.

- the flash events in successive products do not necessarily have
  monotonically increasing times.  Here is one example from today:

  USPLN-LIGHTNING,2006-09-20T18:03:00,2006-09-20T18:03:00
  2006-09-20T18:01:41,30.1556348,-76.0677824,-57.5,1
  2006-09-20T18:01:41,30.1379217,-76.0550704,-21.2,1
  ...
  2006-09-20T18:02:38,38.5449461,-112.6779079,-12.5,1
  2006-09-20T18:02:38,38.544943,-112.6779094,-4.0,1
  2006-09-20T18:02:40,19.3777474,-81.5729318,-16.5,1

  USPLN-LIGHTNING,2006-09-20T18:04:00,2006-09-20T18:04:00
  2006-09-20T18:02:38,38.5433898,-112.6760623,-5.4,1
  2006-09-20T18:02:40,30.0929043,-72.8232306,-59.2,1

  As you can see, the time of the last flash in the first product
  listed is 18:02:40, and the time of the first flash in the
  next product is 18:02:38.  There are lots more examples of this.
  This would be a problem for the way I store the decoded data
  in McIDAS MD files which were designed so that each flash event
  has a later time (or identically equal) to the one before.

- We see instances of negative latitudes.  Here is one example:

  USPLN-LIGHTNING,2006-09-20T18:04:00,2006-09-20T18:04:00
  2006-09-20T18:02:38,38.5433898,-112.6760623,-5.4,1
  ...
  2006-09-20T18:02:50,11.9818748,-77.0828912,-41.6,1
  2006-09-20T18:02:52,-11.5248814,-75.0009061,-49.1,1
  2006-09-20T18:02:53,26.6413964,-80.3567594,0.0,1

  Is the second from the bottom flash really for 11.5248814 south
  latitude?  An even more southern event is:

  USPLN-LIGHTNING,2006-09-20T18:22:00,2006-09-20T18:22:00
  2006-09-20T18:20:45,36.6268659,-110.1519265,-7.4,1
  ...
  2006-09-20T18:21:03,26.707163,-77.2537731,-17.3,1
  2006-09-20T18:21:05,-36.2877797,-66.4969404,-143.6,1
  2006-09-20T18:21:05,10.229565,-84.9955478,-37.5,1

  I have seen flash events reported for -27, -47, and -55 latitude.
  Are these correct, or are they artifacts?  (If they are correct,
  why are there so few events given the number of thunderstorms
  in South America?)

I will be creating a special version of my McIDAS NLDN lightning
decoder for the USPLN data tomorrow.  This one will will leave
out the cloud-to-cloud flashes so I can directly compare the NLDN
data with the USPLN data over active CONUS regions.

Stay tuned, more at 11 ;-)

Cheers,

Tom
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Ticket Details
===================
Ticket ID: TVM-187420
Department: Support Datastream
Priority: Normal
Status: Closed