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[IDD #BLE-413085]: [IDD #ZQK-275228] RE: NLDN data set

Hi Jennifer,

re: REQUEST line for NLDN data from UAlbany
> Thanks, Tom —

No worries.

re:
> I was just composing a message to you about this!

Great minds think alike ;-)

re:
> I’ve got the REQUEST set up in ldmd.conf, but I am baffled by regular 
> expressions and
> not sure what to put in the pqact.conf file. Copying from some other entries 
> already
> there, I have guessed the following, but what should I put instead of ??? if 
> I want
> files to have the filename convention 'data/lightning/YYYYMMDDHH.ndln’
> 
> LIGHTNING
> ^???
> STDIOFILE  data/lightning/(\2:yyyy)(\2:mm)\1\2.nldn

Here is an example pattern-action file action that should produce the output
structure that you want:

# What the NLDN LIGHTNING Product IDs look like:
#
# 2017241194423
# 2017241194524
# 2017241194624
# 2017241194724
#
# This is:
#
# CCYYJJJHHMMSS -
#                 CC  - century
#                 YY  - year
#                 JJJ - Julian day, 001 - 366
#                 HH  - hour
#                 MM  - minute
#                 SS  - second
#
# Notice that the files represent minute-by-minute reports.  Be aware, however,
# that there can be products that only have "heartbeats" in them (meaning
# no actual lighting flash data).

# What an action that matches your example could look like:
#
# NLDN Lightning data from UAlbany
LIGHTNING       
^([12][0-9][0-9][0-9]|[0-9][0-9])([0-3][0-9][0-9])([0-2][0-9])([0-5][0-9])([0-5][0-9])
        FILE
        data/lightning/\1(\1:mm)\3\4.nldn

NB: I am not absolutely positive about the (\1:mm) construct working with the
year; the construct typically keys off of the month, but Julian days, not
months are part of the Product IDs.  I'd give this pattern a try and let us
know if it does not do what you want.

re:
> Also, is there a place to download the decoding software? The doc page
> (https://www.unidata.ucar.edu/data/lightning/nldn.html) is pretty clear about
> what’s in the fine, but it might be nice to not have to re-invent the wheel...

Ah, here's the rub:  decoding into what format?

Unidata GEMPAK comes with a GEMPAK decoder, dcnldn, that will convert the data
in the binary products to GEMPAK format.  Our GEMPAK distribution also
comes with an LDM pattern-action file action for NLDN decoding into 
GEMPAK point files.

The ldm-mcidas set of decoders has a decoder, lgt2md, that will convert the
data in the binary products into McIDAS format.  Unidata McIDAS comes with
an action for NLDN decoding into McIDAS MD files.

We do not have a decoder that converts the binary NLDN data into netCDF. If this
is what you are looking for, I advise you to send an email to the address@hidden
list to see if someone in the community has a routine that you can use straight 
away.

By the way, since this conversation has now turned to how to deal with the NLDN 
products,
I am going to make all further exchanges public so that answers to questions 
asked
can benefit others.

Cheers,

Tom
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Ticket Details
===================
Ticket ID: BLE-413085
Department: Support IDD
Priority: Normal
Status: Closed
===================
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