[gradsusr] Cannot contour grid - all undefined values - GRADS

[Anil Kumar Sharma]

Jennifer,

*thanks. you pointed out accurate.*
I did not take it seriously. I had missed the underlying knowledge of model
NCEP is using for Data.
 NCEP follow Global RTOFS ocean model and is based on an eddy resolving
1/12° global HYCOM (HYbrid Coordinates Ocean Model). NetCDF has 32 hybrid
layers and a horizontal grid size of (4500 x 3298) .Also the grid has an
Arctic bi-polar patch north of 47°N and a Mercator projection south of 47°N
through 78.6°S <http://polar.ncep.noaa.gov/global/about/>.

As you have stated to Create PDEF
<http://www.iges.org/grads/gadoc/pdef.html#rotation>file for interpolation.
But while viewing PDEF
<http://www.iges.org/grads/gadoc/pdef.html#syntax>syntax,
I can see NPS and SPS (Polar stereographic projections) for NCEP data, But
I can not see any PS projection in netCDF file
guide<http://polar.ncep.noaa.gov/global/about/>.
Can you help me in this or to get this working,

*Overall aim with NetCDF file:*
To plot axis of current and data and export it to image or kml file with
GrADS and overlay on google map.

Please lead me in this, if my approach is wrong to plot current in google
map.

B/Rgds
Anil Kumar

On Tue, Dec 17, 2013 at 7:14 PM, Jennifer Adams <jma at cola.iges.org> wrote:

> Hi, Anil --
> This is not a silly problem. The sdfopen command opens this file because
> it has coordinates that have an attribute named "axis" with values of "X",
> "Y", and "T". This is enough information for GrADS to decide to map those
> to LON, LAT, and TIME. Unfortunately, the actual grid latitude and
> longtidue values are 2-dimensional data values, and so the mapping returned
> by sdfopen is for the abstract grid, not the real lat/lon grid. Here is the
> relevant info from the ncdump output:
>
>        float Latitude(Y, X) ;
>                 Latitude:standard_name = "latitude" ;
>                 Latitude:units = "degrees_north" ;
>         float Longitude(Y, X) ;
>                 Longitude:standard_name = "longitude" ;
>                 Longitude:units = "degrees_east" ;
>
> This is a curvilinear grid, so GrADS will not handle it properly without
> some intervention. Go ahead and 'display latitude' after opening the file
> with sdfopen and you will see how the contours bend at high northern
> latitudes. If you are not interested in data that is northward of ~45N (the
> approximate latitude where the grid starts to curve), then you could
> truncate the grid and only look at the gridpoints where the grid values are
> rectilinear. Otherwise, you will need a PDEF file to interpolate. I have
> used ESMF's RegridWeightGen tool to do this for CMIP5 data that are on
> curvilinear grids. Details about that workflow are in
> ftp://cola.gmu.edu/pub/jma/cmip5. Depending on how ambitious you are, you
> can try to adapt these scripts to this data set.
>
> --Jennifer
>
>
>
> On Dec 17, 2013, at 5:50 AM, Anil Kumar Sharma wrote:
>
> *Hi All,*
> *This might be silly problem, but I am Stuck.*
> *I have NetCDF file downloaded from NCEP
> <http://nomads.ncep.noaa.gov/pub/data/nccf/com/rtofs/prod/rtofs.20131216/>containing
> ocean current components. When I opened NetCDF using SDFOpen command in
> Grads*
>
> *ga-> sdfopen C:\t1\20131212_rtofs_glo_2ds_n024_daily_prog.nc
> <http://20131212_rtofs_glo_2ds_n024_daily_prog.nc/>*
>
> *It gave the text on screen*
>
> Scanning self-describing file:  C:\t1\
> 20131212_rtofs_glo_2ds_n024_daily_prog.nc
> SDF file C:\t1\20131212_rtofs_glo_2ds_n024_daily_prog.nc is open as file 1
> LON set to 1 4500
> LAT set to 1 3298
> LEV set to 1 1
> Time values set: 2013:12:10:0 2013:12:10:0
> E set to 1 1
>
> *I can see LON value upto 4500, and LAT value upto 3298. *
>
> *I want to plot current variables for*
> *          longitude  -179 - 179 degree*
> *          latitude -89 to 89 degree*
>
> So what I need to change or How can I get this working??
> when I set these values using SET command
> ga-> set lon -179 179
> LON set to -179 179
> ga-> set lat -89 89
> LAT set to -89 89
> ga-> d skip(u_velocity,5,5);skip(v_velocity,5,5)
> its gives me error
>
> *Cannot contour grid - all undefined values.*
>
>
> *Please lead me.*
>
> *Thanks in Advance !!!*
>
> *B/Regards,*
> *Anil Kumar*
> *Pune, India*
> _______________________________________________
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>
>
>  --
> Jennifer M. Adams
> Center for Ocean-Land-Atmosphere Studies (COLA)
> 111 Research Hall, Mail Stop 2B3
> George Mason University
> 4400 University Drive
> Fairfax, VA 22030
>
>
>
>
>
>
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>
>


-- 
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*Regards, Anil Kumar,Software DeveloperSmartBuzzInc 17B, Chd *
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