20051016: Gempak - Extracting point data from GEMPAK grid

>From: "John Meyers" <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200510170024.j9H0Oc6B007461

>Institution: Museum of Science, Boston MA
>Package Version: 5.8.3a
>Operating System: RHEL4
>Hardware Information: Dual Opteron
>Inquiry: In order to import some data into Flash format for our website, I nee
> d to extract individual parameter values at specific coordinates in Gempak gr
> ids (or NetCDF if not possible in Gempak).  For example, how can I return the
>  surface temperature at a specific lat/lon point in the RUC2 grid for a speci
> fic forcast hour?  I've looked at GDLIST but can't quite figure out how to do
>  it for one point.
>

John,

The easiest way to extract grid point data for a level/time at a specific
station or lat/lon is to use the program GDPOINT.


 GEMPAK-GDPOINT>l
 GDATTIM  = f000
 GDFILE   = ruc2
 GLEVEL   = 2
 GPOINT   = bos
 GVCORD   = hght
 GFUNC    = tmpf
 SCALE    = 0
 GEMPAK-GDPOINT>r
 
GDFILE: $MODEL/ruc/2005101715_ruc236.gem                  
GPOINT: bos                                               
GVCORD: hght                                              
GLEVEL: 2                                                 
GFUNC : tmpf                                              
SCALE : 0                                                 
     051017/1500F000 :     54.82568

or

GDATTIM = FALL
 GEMPAK-GDPOINT>r
 
GDFILE: $MODEL/ruc/2005101715_ruc236.gem                  
GPOINT: bos                                               
GVCORD: hght                                              
GLEVEL: 2                                                 
GFUNC : tmpf                                              
SCALE : 0                                                 
     051017/1500F000 :     54.82568
     051017/1500F001 :     56.78081
     051017/1500F002 :     57.28056
     051017/1500F003 :     57.80221
     051017/1500F004 :     58.20769
     051017/1500F005 :     58.04918
     051017/1500F006 :     56.89297
     051017/1500F009 :     52.16292

This method would be easy to implement in a CGI or other request process.

If you were to need many stations converted at one time, then you can
use GDGSFC to interpolate grid point data to a surface file at station locations
for retreival with SFLIST.

Steve Chiswell
Unidata User Support

>
>
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