20020122: gempak ltg gridding

Brian,

Unfortunately, you cannot enter a time range for gdattim
in GDDIAG. You can make your shell script loop through the times,
or create a program to do it internally. You probably will have to be careful
in gddiag not to overwrite a grid that you are using as input.

The GDSTAT program almost does what you want already. It computes
the avarage, standard deviation, and number of observations
for a time series. The total of a field ODEN would be
MUL(AVGODEN,NUMODEN). Or, the program could be modified to save the TOT
total that is used for the average.


Steve Chiswell
Unidata User Support



>From: Brian Colle <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200201230006.g0N06Rx14260

>
>Hi,
>
>A while back you helped me the lightning counting program below. It works
>great for plotting, but now I want to add up all the strikes within a grid
>for a certain time period. I am trying to do this using the gddiag
>program:
>
>#!/bin/csh -f
>#
>gddiag << xxx
>GDFILE   = june.grd
>GDOUTF   = june.grd
>GFUNC    = add(odentot^000601/0000,oden)
>GDATTIM  = ALL
>GLEVEL   = 0
>GVCORD   = none
>GRDNAM   = odentot
>GPACK    = 
>run
>
>exit
>xxx
>exit
>
>but I am having problems with the GDATTIM. It appears that GDATTIM 
>doesn't recognize ALL, and 000601/0005-000630/2355 does not seem to work
>for me either. If I set GDATTIM=000601/0005 it works ok. Before I
>write a program to loop through all the 5 minute times in the file, I just
>wanted to make sure I wasn't missing something subtle with GDATTIM?
>
>Thanks for your time.
>
>Brian
>
>On Wed, 24 Oct 2001, Unidata Support wrote:
>
>> 
>> Brian,
>> 
>> I have created a program called GDOBSCNT that will find the
>> number of observations within a specified radius of each grid
>> point and store the grid as parameter ODEN@0%none for each 
>> time specified from the input surface file.
>> 
>> You can download the tarfile from:
>> http://www.unidata.ucar.edu/packages/gempak/contrib/gdobscnt.tar.Z
>> 
>> In your GEMPAK 5.6 $NAWIPS directory, unpack the tarfile with:
>> 
>> zcat gdobscnt.tar.Z | tar xvf -
>> 
>> Then build and install with:
>> 
>> cd $NAWIPS/unidata/programs/gdobscnt
>> make clean
>> make all
>> make install
>> make clean
>> 
>> 
>> To use the program, you should first create your grid file with your 
>> required grid spacing using GDCFIL. 
>> 
>> The program uses 4 parameters. SFFILE, DATTIM, GDFILE, RADIUS.
>> SFFILE is your input surface (NLDN) file. GDFILE is the
>> file for the grids to be stored. DATTIM is the times
>> (a list, range, single, or all) from the surface file
>> to process. RADIUS is the range, in meters, from the
>> each grid point that stations will be counted.
>> 
>> The result is a grid called ODEN for each time specified
>> by DATTIM.
>> 
>> For example, using today's 1630Z NLDN file (which contains
>> nldn bins at 5 minute intervals from 1630Z to 1655Z), and a grid 
>> file I have already created called test.grd specifying a 50KM
>> radius (50000m):
>> 
>> % gdobscnt
>>  SFFILE    Surface data file                 nldn|011024/1630
>>  DATTIM    Date/time                         all
>>  GDFILE    Grid file                         test.grd
>>  RADIUS    Radius (in meters) to search      50000
>>  Parameters requested: SFFILE,DATTIM,GDFILE,RADIUS.
>>  GEMPAK-GDOBSCNT>r
>>  Processing 011024/1630    
>>  Processing 011024/1635    
>>  Processing 011024/1640    
>>  Processing 011024/1645    
>>  Processing 011024/1650    
>>  Processing 011024/1655    
>>  Parameters requested: SFFILE,DATTIM,GDFILE,RADIUS.
>>  GEMPAK-GDOBSCNT>e
>> 
>> I can then plot the data, with grid point values and contous in GDPLOT2
>> with:
>>  GDFILE   = test.grd
>>  GDATTIM  = 1630-1655
>>  GLEVEL   = 0
>>  GVCORD   = none
>>  PANEL    = 0
>>  SKIP     = 0
>>  SCALE    = 0
>>  GDPFUN   = ODEN
>>  TYPE     = cm
>>  CONTUR   = 0
>>  CINT     = 0
>>  LINE     = 3
>>  FINT     = 
>>  FLINE    = 
>>  HILO     =  
>>  HLSYM    =  
>>  CLRBAR   = 1
>>  WIND     = 
>>  REFVEC   =  
>>  TITLE    = 1
>>  TEXT     = 1
>>  CLEAR    = y
>>  GAREA    = 34.0;-95.2;43.7;-79.2
>>  PROJ     = LCC/25.0;-90.0;25.0
>>  MAP      = 1
>>  LATLON   = 0
>>  DEVICE   = XW
>>  STNPLT   =  
>>  SATFIL   =  
>>  RADFIL   =  
>>  LUTFIL   =  
>>  STREAM   =  
>>  POSN     = 0
>>  COLORS   = 5
>>  MARKER   = 0
>>  GRDLBL   = 0
>>  FILTER   = 0
>>  GEMPAK-GDPLOT2>r
>> Creating process: xw for queue 12551
>>  [TG 0] 1630-1655
>>  Number of times =            6
>>             1 011024/1630
>>             2 011024/1635
>>             3 011024/1640
>>             4 011024/1645
>>             5 011024/1650
>>             6 011024/1655
>> <etc...>
>> 
>> The TYPE=cm in gdplot2 will plot both the contours of the data as well as
>> the data values at the grid point locations (marker=0).
>> 
>> Let me know if you have questions/problems/etc.
>> 
>> Steve Chiswell
>> Unidata User Support
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> >From: Unidata Support <address@hidden>
>> >Organization: UCAR/Unidata
>> 
>> >
>> >Brian,
>> >
>> >The ltgmap program was the same program as sfmap. It just allowed a 
>> >greater number of times/observations. In GEMPAK 5.6, I increased
>> >the number of times/observations in sfmap so that a separate ltgmap program
>> >wasn't needed.
>> >
>> >The lat/lon locations are the station locations (each lightning strike
>> >is treated as a "ship" report).
>> >
>> >I can create a program in the next few days that will read the surface file
>  
>> >and create the grid of "reports within a DELTA radius".
>> >
>> >Steve Chiswell
>> >Unidata User SUpport
>> >
>> >
>> >
>> >
>> >
>> >>From: Brian Colle <address@hidden>
>> >>Organization: UCAR/Unidata
>> >>Keywords: 200110222134.f9MLY8102451
>> >
>> >>
>> >>Steve,
>> >>
>> >>> 
>> >>> Brian,
>> >>> 
>> >>> At this point in time, there is nothing within GEMPAK
>> >>> to make this type of computation as you require.
>> >>> 
>> >>> I would be possible to write a program to accumulate the number
>> >>> of strikes within a given radius of a grid point.
>> >>>
>> >>
>> >>In order to write another program I need to know how to open and
>> >>read the ltg sfc file to extract the lat/longs for each lightning strike,
>> >>assuming that they are stored that way. Just to clarify, is there a gempak
>> >>fortran subroutine that will read the file and extract this information?
>> >>For example, I used to use ltgmap, which plotted the individual lightning
>> >>strikes. I was hoping that I could take advantage of the way ltgmap reads
>> >>in the data, but only use the lat/long info. I notice that the latest
>> >>version of gempak doesn't even use ltgmap anymore?
>> >> 
>> >>> The other limitation you would have is that a 3km grid is going
>> >>> to be a very large grid if you are attempting to cover the
>> >>> entire country with a single grid. At present time, the default
>> >>> maximum number of grid points in a file is 400,000.
>> >>> A 4km national grid is approximately 1,200,000 points.
>> >>> 
>> >>> If you are doing a regional (or series of regional) grids
>> >>> then that won't be a problem.
>> >>> 
>> >>
>> >>Yes, I only want the regional NE US.
>> >>
>> >>Thanks again,
>> >>
>> >>Brian
>> >>
>> >>> >
>> >>> >Hi,
>> >>> >
>> >>> >I have some gempak lightning data (surface files of sgnl strength) that
>  I
>> >>> >want to interpolate to a uniformly spaced 3-km gempak grid such that ea
> ch
>> >>> >grid point has the number of nearby strikes. With this gridded file I c
> an
>> >>> >then contour the number density up in gempak. 
>> >>> >
>> >>> >Do you have any ideas or sample code how I can do this interpolation 
>> >>> >of lightning data within gempak or interfacing gempak with f77? 
>> >>> >
>> >>> >I appologize in advance for the loaded question, but I am looking
>> >>> >for ideas at this point.
>> >>> >
>> >>> >Thanks for your time...
>> >>> >
>> >>> >Brian
>> >>> >____________________________________________________________
>> >>> >Prof. Brian Colle         INTERNET: address@hidden
>> >>> >(631)632-3174
>> >>> >Institute for Terrestrial and Planetary Atmospheres
>> >>> >Marine Sciences Research Center
>> >>> >State University of New York at Stony Brook
>> >>> >Stony Brook, NY 11794-5000
>> >>> >
>> >>> 
>> >>> ************************************************************************
> ***
>> > *
>> >>> Unidata User Support                                    UCAR Unidata Pro
> gra
>> > m
>> >>> (303)497-8644                                                  P.O. Box 
> 300
>> > 0
>> >>> address@hidden                                   Boulder, CO 8
> 030
>> > 7
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>> >>> 
>> >>
>> >
>> >
>> 
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>> (303)497-8644                                                  P.O. Box 3000
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>