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20050506: NLDN gempak data

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  • Subject: 20050506: NLDN gempak data
  • Date: Fri, 6 May 2005 13:26:55 -0600 (MDT)
David,

If you have the source distribution, you have the file
$NAWIPS/unidata/ldmbridge/dcnldn/nldn.pack.full
which provides for more parameters than the nldn.pack which just
has SGNL and MULT. I have attached to this message if you
need it.

Replace your $GEMTBL/pack/nldn.pack file with this.

The parameters TSEC and MSEC are: time in seconds of the flash from
00Z that day. MSEC is milliseconds from TSEC.

For example,
 GEMPAK-SFLIST>r
 PARM = TSEC;MSEC;SGNL;MULT;SMAJ;ECNT;ANGL;CHI2

    STN    YYMMDD/HHMM      TSEC     MSEC     SGNL     MULT     SMAJ     ECNT
                            ANGL     CHI2
      -    050506/1900  68406.00   300.00   -40.00     7.00     0.00     0.00
                            0.00     0.00

The 68406 seconds is that number of seconds since 050506/0000, which is
19 hr 00 min 06 sec (and 300 milliseconds). The actual data has seconds
since Jan 1, 1970, but this is chopped to seconds in the current day
by the decoder (since you wouldn't be able to SFLIST the value otherwise
without getting ****** characters)- and this sort of goes with the julian
day convention of the file names.

The shortened version of nldn.pack was used historically due to sites not
having enough CPU speed to decode/store the number of strikes during the
summer, but that is probably not an issue these days, so I'll make the
full packing table the default in the next release.

Steve Chiswell
Unidata User Support

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On Fri, 6 May 2005, David Fitzgerald wrote:

> Hi,
>
>
>
> We are using 'sflist' to pull out the signal strength, polarity, lat/lon and
> time of each lightning strike in the nldn data in gempak format.  We plan on
> using this data in some GIS applications but we need better time resolution
> of the data.  The 'stim' parameter gives the time in hhmm form, but I need
> to resolve each strike down to the second. So my questions:  Does the nldn
> data store the lightning data time down to the second?  If so how can I pull
> the seconds out?
>
>
>
> Thanks!!
>
>
>
> Dave
>
>
>
> *********************************************
>
> David Fitzgerald
>
> Distributed System Specialist II
>
> Millersville University
>
> Millersville PA 17551
>
> Phone: 717-871-2394
>
> Fax:     717-871-4725
>
> E-mail: address@hidden
> <mailto:address@hidden>
>
>
>
> Oh, so they have internet on computers now!
>
>                                          -- Homer Simpson
>
>
>
>
>
>
TSEC    0       100000          1
MSEC    0       1000            1
SGNL    -99999. 999999.         0.1
MULT    0       999999          1
SMAJ    -99999  999999          1
ECNT    -99999  999999          1
ANGL    0       360             1
CHI2    -99999  999999          1