Re: [gembud] Creating composite from tgftp.nws.noaa.gov

Hi John - we do the same thing here that you are looking to do.  We create 
national radar using nex2gini. 

We found that nex2gini "knows" where to look for the individual site radar 
files using the setting found in $GEMTBL/config/datatype.tbl in the line 
beginning with NEXRIII.

So when you pull one of these radar files from the ftp site, it should 
"land" in the directory using the format in the second column of that 
line.  For example the second column in that line of datatype.tbl is 
$RAD/LOCAL/%SITE%/%PROD% -- which means if we pull a radar file from 
Taunton, MA it lands in the $RAD/LOCAL/BOX/BREF1 directory in the format 
BREF1_YYYYMMDD_HHMM.   (Forgive me if you know this already but dont 
forget $RAD is defined in the Gemenviron file in your home directory of 
GEMPAK.. and we established that all of our "local" radar data -- that is 
the radar data from any one site -- would sit in a $RAD/LOCAL dir).

The trick here is when you pull an "sn.last" file from the ftp server the 
first two lines of the file contain the site ID and the DDHHMM info in the 
headers.  We decode those to help form the correct YYYYMMDD_HHMM string to 
name the file that lands in the $RAD/LOCAL/BOX/BREF1 directory.

For example if you pull a sn.last file and look at its first two lines you 
might see
SDUS51 KBOX 091259
N0RBOX

We will will place this in our $RAD/LOCAL/BOX/BREF1 directory as 
BREF1_20120809_1259.   TIP -  although you can use the system time to 
provide the 201208 (year and month info) we use the time that particular 
sn.last file was posted on teh ftp server (we pull these using wget and 
first pull a directory listing to get the post time then the file itself).

Once you've done that for all the latest sn.last files on the ftp server 
you are ready to generate a composite using nex2gini - which can be real 
touchy:

SATFIL is the name of the output file that will be created -- and WONT 
write an output file if there are upper case chars in the output path you 
provide (gives a -3 error) - ours is natl_raw_YYYYMMDD_HHNN where here the 
YYYYMMDD_HHNN is literally that character string - nex2gini figures out 
using the system time how to fill that in with year month date hour minute 
info. 

GFUNC can be either upper or lower case but has to match the %PROD% subdir 
in the NEXRIII alias (for us its BREF1 or bref1)

our GRDAREA, PROJ, KXKY, settings are as follows
GRDAREA=19.315;-121.415;49.5727;-62.4067
PROJ=lcc/38;-98;38
KXKY=4300;3000

CPFIL is blank and we use a RADTIM=current, RADDUR=20 (ignores radar 
images more than 20 minute older than the system -- or current time).  Our 
RADMOD=pc (we want both precip and clear air mode data in the composite). 
We also use compress=yes and a radfrq=0 as if radfrq is not zero the 
program will repeat every n minutes. 

This isnt  the whole story for the individual file though - inorder for 
them to be displayed in NMAP2 and gpmap because we were naming these 
individual site files "BREF1_YYYYMM files, we had to be sure the file 
$GEMTBL/unidata/nex2gini.tbl had a line in it for BREF1 data - ours was 
BREF1 27 1 dbz,0,105,-30,75 TICZ99 CHIZ   where the 27 is a band and the 
DBZ is the header that gets plotted on the colorbar when displaying the 
individual (not composite) site radar data.  That number 27 was important 
because it linked it to a file $GEMTBL/sat/imgtyp.tbl which has an entry 
RADAR N0R 0 105 11 2**26 bref1_ref.tbl -- the first word is the image 
type, the second is the image content, the next two are seemingly min/max 
scale values. The word with the asterisks is in the format 2**bandminus1 
--- well our band is 27 so that is why we have 2**26 and the last word is 
the enhancement that will be applied to this type of image (we created our 
own called bref1_ref.tbl and stuffed it in $GEMTBL/luts  directory.

That was easy wasnt it?

You should have enough here to do what you need but it will take some 
trial and error.  Good luck.

Pete




From:   John Coryat <coryat@xxxxxxxxx>
To:     gembud@xxxxxxxxxxxxxxxx
Date:   08/08/2012 05:58 PM
Subject:        [gembud] Creating composite from tgftp.nws.noaa.gov
Sent by:        gembud-bounces@xxxxxxxxxxxxxxxx



I'm working on a creating composites for the US using NEXRAD level III 
data at 10 minute intervals.

I'm having a problem taking the data from NOAA's ftp site to the correct 
location and file format in GEMPAK.

I would like to know how I can store and process data from NOAA's site:

ftp://tgftp.nws.noaa.gov/SL.us008001/DF.of/DC.radar/DS.p94r0/SI.<station 
id>/sn.last

into GEMPAK using gdplot3, nex2img or ?

Thanks in advance for any assistance in this matter.

-John Coryat_______________________________________________
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