[gradsusr] netCDF control file
Heiner Körnich
heiner at misu.su.se
Tue Nov 9 08:33:08 EST 2010
Hi Deniz,
ok. When you tried to open the file with sdfopen and it failed, this means
that the file is not consistent with the coards-standard. So we need a
ctl-file and xdfopen.
You need the name of all coordinates of the file. ncdump -h would give that.
When you wrote "dimension1", this is just an example for the first
dimension. Probably, this should be the name of your longitude-variable in
matlab, eg. "long" or "x" or so.
"fwrite" in matlab follows the logic of the programming language c. You have
to open the file first with fopen. It is explained in the matlab-manual.
Here is an example from me:
% open the file 'ures.bin' in binary write-mode.
fid=fopen('ures.bin','wb');
% write binary data from the field winds to file in real*4 %precision
fwrite(fid,winds,'real*4');
Regards,
Heiner
On Tue, Nov 9, 2010 at 1:37 PM, Deniz Demirhan Bari <bari at iap-kborn.de>wrote:
> Dear Heiner,
>
> Grads 2.0 in our server is now changed and it is compiled with netCDF
> support.
>
> When I tried:
>
> >sdfopen ures.nc
>
> it says:
>
> >Scanning self-describing file: ures.nc
>
> gadsdf: SDF file has no discernable X coordinate.
>
> When I try:
>
> >xdfopen ures.ctl
>
> >Scanning Descriptor File: ures.ctl
>
> gadsdf: Lon dimension dimension1 is not an SDF dimension.
>
> SDF Descriptor file ures.ctl was not successfully opened & parsed.
>
>
>
> ---Matlab fwrite, I tried it but couldn’t manage.
>
> Thank you
>
> Deniz
>
> *Von:* gradsusr-bounces at gradsusr.org [mailto:gradsusr-bounces at gradsusr.org]
> *Im Auftrag von *Heiner Körnich
> *Gesendet:* Montag, 8. November 2010 17:07
>
> *An:* GrADS Users Forum
> *Betreff:* Re: [gradsusr] netCDF control file
>
>
>
> Hi Deniz,
>
> when you write recognized "sdfopen" or "xdfopen", do you mean that grads
> does not know the command? Is your grads-version compiled with
> netcdf-support?
>
> It is certainly a good thing to create netcdf-files, as they are
> self-descriptive. But still you could write binary data from matlab with the
> command fwrite:
> http://www.mathworks.com/help/techdoc/ref/fwrite.html
>
> Then you have to follow the logic of grads binary files, ie. first
> longitude, then latitude, then height, then time, as described in the
> manual.
>
> So far,
> Heiner
>
> On Mon, Nov 8, 2010 at 4:25 PM, Deniz Demirhan Bari <bari at iap-kborn.de>
> wrote:
>
> Hello Heiner,
>
> Thank you for your mail. I tried 'sdfopen ures.nc' but neither grads 2.0
> nor grads 1.8 recognized sdfopen. Then I prepared a control file as below,
> by looking at the “CDO sinfo ures.nc”. Then tried “xdfopen ures.ctl” but
> none of the grads versions recognized xdfopen again.
>
> *
>
> DSET ^ures.nc
>
> DTYPE netcdf
>
> UNDEF -9e+33
>
> XDEF dimension1 96 LINEAR 0.000000 3.750000
>
> YDEF dimension2 48 LEVELS -87.159 -83.479 -79.777 -76.070 -72.362 -68.652
>
> -64.942 -61.232 -57.521 -53.810 -50.099 -46.389
>
> -42.678 -38.967 -35.256 -31.545 -27.833 -24.122
>
> -20.411 -16.700 -12.989 -9.278 -5.567 -1.856
>
> 1.856 5.567 9.278 12.989 16.700 20.411
>
> 24.122 27.833 31.545 35.256 38.967 42.678
>
> 46.389 50.099 53.810 57.521 61.232 64.942
>
> 68.652 72.362 76.070 79.777 83.479 87.159
>
> ZDEF dimension3 114 LINEAR 1 1
>
> TDEF dimension4 1 LINEAR 00:00Z00jan0000 1mn
>
> TITLE ures.grb T31 grid
>
> VARS 1
>
> ures 114 1,100 ures
>
> ENDVARS
>
> *
>
>
>
> My data is three dimensionaI and if I try to save my data in an ASCII file
> in MATLAB it gives a two dimensional output. I also couldn’t solve this
> problem
>
> Thank you
>
> Deniz
>
>
>
>
>
> *Von:* gradsusr-bounces at gradsusr.org [mailto:gradsusr-bounces at gradsusr.org]
> *Im Auftrag von *Heiner Körnich
> *Gesendet:* Montag, 8. November 2010 14:06
> *An:* GrADS Users Forum
> *Betreff:* Re: [gradsusr] netCDF control file
>
>
>
> Hi Deniz,
>
> you don't nead a ctl-file to open a netcdf-file in grads. If your file
> follows the COARDS-standard, then you can open it with 'sdfopen ures.nc'.
> If grads won't recognise it, you might want to try an older grads-version.
> We had some problems here with grads 2.0 and netcdf.
>
> If grads still won't open your file, you can write a ctl-file and try to
> open that with the command 'xdfopen'. The ctl-file looks a bit different
> from standard ctl-files, look here:
> http://www.iges.org/grads/gadoc/gradcomdxdfopen.html
>
> Then, you would need the output from ncdump in order to know what is inside
> the netcdf-file. Alternatively you can use the climate data operators (CDO)
> with the command "cdo sinfo ures.nc".
> Or in matlab, if you have the mexnc-package installed, you read the
> information with
> info=nc_info('ures.nc')
> Then you can access all details in info.
>
> Finally, if it is only you who will use the data, it might be simpler to
> write binary output in matlab and use a standard ctl.
>
> Kind regards from Stockholm,
> Heiner
>
> On Mon, Nov 8, 2010 at 10:11 AM, Deniz Demirhan Bari <bari at iap-kborn.de>
> wrote:
>
> Dear Grads users,
>
> I have calculated residual wind components in MATLAB and saved them in
> netCDF file. Now I want to read them in grads but I cannot create a netcdf
> control file.
>
> I tried to get the output of ncdump but my computer doesn’t recognize ncdump although I installed it.
>
> I am using the latest version of Grads on a Suse Linux computer.
>
> My attempt to create a ctl file is below:
>
> *
>
> DSET ^ures.nc
>
> DTYPE netCDF
>
> XDEF 96 LINEAR 0.000000 3.750000
>
> YDEF 48 LEVELS -87.159 -83.479 -79.777 -76.070 -72.362 -68.652
>
> -64.942 -61.232 -57.521 -53.810 -50.099 -46.389
>
> -42.678 -38.967 -35.256 -31.545 -27.833 -24.122
>
> -20.411 -16.700 -12.989 -9.278 -5.567 -1.856
>
> 1.856 5.567 9.278 12.989 16.700 20.411
>
> 24.122 27.833 31.545 35.256 38.967 42.678
>
> 46.389 50.099 53.810 57.521 61.232 64.942
>
> 68.652 72.362 76.070 79.777 83.479 87.159
>
> ZDEF 114 LINEAR 1 1
>
> TDEF 1 LINEAR 00:00Z00jan0000 1mn
>
> OPTIONS yrev
>
> UNDEF -9e+33
>
> VARS 1
>
> ures 114 1,100 ures
>
> ENDVARS
>
> *
>
> Thanks in advance
>
> Deniz DEMIRHAN BARI
>
> Leibniz-Institut für Atmosphärenphysik e.V.
> an der Universität Rostock
> Schlossstraße 6
> 18225 Kühlungsborn
>
>
>
>
>
>
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>
>
>
> --
> Heiner Körnich
> Dept. of Meteorology Tel: +46 8 164333
> Stockholms University, SE-106 91 Stockholm, Sweden
> Email: heiner at misu.su.se www.misu.su.se/~heiner/<http://www.misu.su.se/%7Eheiner/>
>
>
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>
>
>
>
> --
> Heiner Körnich
> Dept. of Meteorology Tel: +46 8 164333
> Stockholms University, SE-106 91 Stockholm, Sweden
> Email: heiner at misu.su.se www.misu.su.se/~heiner/
>
> _______________________________________________
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>
>
--
Heiner Körnich
Dept. of Meteorology Tel: +46 8 164333
Stockholms University, SE-106 91 Stockholm, Sweden
Email: heiner at misu.su.se www.misu.su.se/~heiner/
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