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19990305: problems using oagrid

Robert,

The problem you are having with oagrid is that the longitudes for
the grid areas wrap the dateline. You can see this is happening
by looking at your GRID POINTS line below, you will find X = -78.

So the problem you are having with oabsnd is that kx is -78, which
is bogus. That is likely the reason oagrid reports too few stations in
the area as well.

As I mentioned before, you can use gdcfil to create the file you want also.

Here is the fix or oagrid to handle the wrapping of the dateline:
In $GEMPAKHOME/src/programs/oa/oagrid/oagagn.f, you will find:
line 62:
        itst = IFIX ( gltln (4) - gltln (2) )
        nlon = IFIX ( ( gltln (4) - gltln (2) ) /deltax )

Change this to:
        itst = IFIX ( gltln (4) - gltln (2) )
        if(itst.le.0) then
           itst = itst + 360
           nlon = IFIX ( ( gltln (4) - gltln (2) + 360. ) /deltax )
        else
           nlon = IFIX ( ( gltln (4) - gltln (2) ) /deltax )
        endif

After editing this routine, rebuild oagrid with:
cd $GEMPAKHOME/src/programs/oa/oagrid
make clean
make all
make install
make clean

Now when you run oagrid you will get:
 GRID POINTS     X :  35  ( 2, 2 )        Y :  12  ( 2, 2 )

Steve Chiswell


>From: Robert Mullenax <address@hidden>
>Organization: .
>Keywords: 199903060616.XAA03552

>Steve,
>
>Actually I recall now, the first time I tried to do this with a similar area
>like 50;160;75;-120 (or soemthing like that) I did get two few stations
>error.  I then ran it with grdarea=fai-- and the delta's you see below were
>produced.  These were already present when I ran OAGRID again with the 
>grdarea you see below(as described in previous message).  Here is output:
>
> 
>Enter <cr> to accept parameters or type EXIT:
> Parameters requested: GDFILE,DELTAN,DELTAX,DELTAY,GRDAREA,EXTEND,DTAAREA,
> SOURCE,SNFILE,SFFILE,SNPARM,SFPARM,DATTIM,LEVELS,MAXGRD.
> GEMPAK-OAGRID>l
> GDFILE   = $GEMDATA/upperair/test5.grd
> DELTAN   = 6.29
> DELTAX   = 3.15
> DELTAY   = 3.15
> GRDAREA  = 45;150;80;-100
> EXTEND   = 2;2;2;2
> DTAAREA  =
> SOURCE   = sn
> SNFILE   = $GEMDATA/upperair/990306_upa.gem
> SFFILE   = $GEMDATA/HRCBOB.SFC
> SNPARM   = pres;tmpc;dwpc;drct;sknt;hght;hgft
> SFPARM   = SKYC;TMPF;WSYM;PMSL;;DWPF;BRBK
> DATTIM   = 00
> LEVELS   = all
> MAXGRD   = 200
>
>
>                   OBJECTIVE ANALYSIS PARAMETERS
> 
> GRIDAREA           45.00    150.00     79.65    -98.85  (       80.00
>-100.00)
> DELTAN              6.290
> DELTAX              3.150
> DELTAY              3.150
> 
> GRID POINTS     X : -78  ( 2, 2 )        Y :  12  ( 2, 2 )
> EXTENDAREA           38.70    143.70     85.95    -92.55
> DATAAREA             38.70    143.70     85.95    -92.55
> 
>
> GEMPAK-OAGRID>exit
>
>Thanks,
>Robert Mullenax
>
>